Journal articles on the topic 'Aerospace engineering, n.e.c'

Optimized conditions for the synthesis of fully deprotected (2R)-aziridine containing dipeptides are described. Preparation of fully protected N- and C- terminal aziridine containing dipeptides was found to be straightforward and high yielding for the majority of compounds, whereas their full deprotection was possible only for C-terminal analogs. Deprotection of N-terminal derivatives using standard procedures of peptide chemistry was found difficult providing only mixtures of unidentifiable products. The described molecules have potential as building blocks in synthetic chemistry, in the chemical biology arena, as covalent modifiers, and as biomarkers.

We present gOTzilla, a protocol for interactive zero-knowledge proofs for very large disjunctive statements of the following format: given publicly known circuit C, and set of values Y = {y1 , . . . , yn }, prove knowledge of a witness x such that C(x) = y1 ∨ C(x) = y2 ∨ · · · ∨ C(x) = yn . These type of statements are extremely important for the proof of assets (PoA) problem in cryptocurrencies where a prover wants to prove the knowledge of a secret key sk that associates with the hash of a public key H(pk) posted on the ledger. We note that the size of n in popular cryptocurrencies, such as Bitcoin, is estimated to 80 million. For the construction of gOTzilla, we start by observing that if we restructure the proof statement to an equivalent of proving knowledge of (x, y) such that (C(x) = y) ∧ (y = y1 ∨ · · · ∨ y = yn )), then we can reduce the disjunction of equalities to 1-out-of-N oblivious transfer (OT). Our overall protocol is based on the MPC in the head (MPCitH) paradigm. We additionally provide a concrete, efficient extension of our protocol for the case where C combines algebraic and non-algebraic statements (which is the case in the PoA application). We achieve an asymptotic communication cost of O(log n) plus the proof size of the underlying MPCitH protocol. While related work has similar asymptotic complexity, our approach results in concrete performance improvements. We implement our protocol and provide benchmarks. Concretely, for a set of size 1 million entries, the total run-time of our protocol is 14.89 seconds using 48 threads, with 6.18 MB total communication, which is about 4x faster compared to the state of the art when considering a disjunctive statement with algebraic and non-algebraic elements.

This research addresses a numerical analysis on the effects of flow compressibility on the characteristics of droplet dispersion, evaporation, and mixing of fuel and air according to the simulation of the spatially developing supersonic shear flows laden with evaporating n-decane droplets. A sixth-order hybrid WENO numerical scheme is employed for capturing the unsteady wave structures. The influence of inflow convective Mach number ( M c ), representing the high-speed flow compressibility, on the two-phase mixing is analyzed, in which M c is specified from 0.4 to 1.0. It is found that the shearing vortex is compressed spatially as M c increases, associated with the alternate distributions of compression and expansion regimes in the flow field. The flow compressibility changes not only the vortex structures but also the aerothermal parameters of the shear flows, and further influences the dispersion and evaporation of droplets. The two-phase mixing efficiency is observed to decrease as M c increases.

This work analyses the characteristics of functional coatings obtained by vacuum ion-plasma sputtering. These coatings have three-layer multiphase structure created as a result of condensing aluminium and titanium according to a certain programme. The article presents the results of investigation into the heat-resistance of ion-plasma coatings based on Ti-Al-N for titanium alloy parts of gas turbine engines. Analysis of the oxidation process between a sample surface and coatings within the range of 500–825 °C was carried out. The basic features of the process of coating destruction under high-temperature oxidation conditions were determined by means of scanning electron microscopy. The results of the tests made it possible to state that the coatings developed are able to operate at temperatures of 600–750 °C.

Abstract Traditional zero-knowledge protocols have been studied and optimized for the setting where a single prover holds the complete witness and tries to convince a verifier about a predicate on the witness, without revealing any additional information to the verifier. In this work, we study the notion of distributed-prover zero knowledge (DPZK) for arbitrary predicates where the witness is shared among multiple mutually distrusting provers and they want to convince a verifier that their shares together satisfy the predicate. We make the following contributions to the notion of distributed proof generation: (i) we propose a new MPC-style security definition to capture the adversarial settings possible for different collusion models between the provers and the verifier, (ii) we discuss new efficiency parameters for distributed proof generation such as the number of rounds of interaction and the amount of communication among the provers, and (iii) we propose a compiler that realizes distributed proof generation from the zero-knowledge protocols in the Interactive Oracle Proofs (IOP) paradigm. Our compiler can be used to obtain DPZK from arbitrary IOP protocols, but the concrete efficiency overheads are substantial in general. To this end, we contribute (iv) a new zero-knowledge IOP Graphene which can be compiled into an efficient DPZK protocol. The (D + 1)-DPZK protocol D-Graphene, with D provers and one verifier, admits O(N 1 /c ) proof size with a communication complexity of O(D2 ·(N 1−2 /c +Ns )), where N is the number of gates in the arithmetic circuit representing the predicate and Ns is the number of wires that depends on inputs from two or more parties. Significantly, only the distributed proof generation in D-Graphene requires interaction among the provers. D-Graphene compares favourably with the DPZK protocols obtained from the state-of-art zero-knowledge protocols, even those not modelled as IOPs.

Titanium aluminides have great potential in structural, aerospace, and high temperature engineering applications. In the majority of these uses, it is expected fusion welding will be used as the primary method of joining. However, control of the as-welded microstructure (and mechanical properties) is difficult to obtain since cooling rates and, therefore, the microstructures can vary considerably.Samples of 14.2 Al, 21.3 Nb, 0.018 C, 0.05 Fe, 0.012 N, 0.013 H, and 0.10 O (in wt.%), commonly known as Ti-24Al-11Nb (in at.%), were placed on a copper block and spot welded inside of a Iucite box using a gas tungsten arc welder (GTAW). The specimens were then sealed in argon backfilled fused quartz tubes and heat treated in the α2, + B2 field of the phase diagram. The conditions of this post-weld heat treatment (PWHT) were 982°C for 0.5, 1, 2, or 4 hours. Transmission electron microscopy and microhardness tests were used to characterize the alloy.

High-temperature resistant epoxy adhesives cured under room-temperature becomes more and more important in many industries such as aerospace and aviation, the locomotive and diesel, etc. In this paper three self-made amine-based mannich-amide was mixed with E-44 epoxy resin under the same technological parameters, and the epoxy adhesives cured by the three amine-based mannich-amides under room-temperature are tested by FTIR, TGA and DMA. Results of TGA show a quicker drop in weight occurrence within 150-250°C for epoxy networks cured by multiamine-based mannich amides than the long-chain alkyl one. Results of FTIR show completely curing of epoxy adhesives cured by mannich amides under room temperature and the height of absorption band 1502cm-1(C-N) is much lower after 12h under 150°C,200°C atmosphere than 25°C. Results of DMA show that the Tg determined by DMA has an order EP AN2(89.9°C) >EP AN1(89.7°C)>EP AN3(80.8°C). In the rest results of DMA, the EP-AN3 system has the biggest storage modulus (E’) within 100-150°C while the EP-AN3 system has the smallest loss modulus(E”) within 100-150°C. As a whole, the epoxy adhesives cured by AN3 under room-temperature have the best high temperature resistance.

In order to identify the nonlinear characteristics of the magnetorheological (MR) damper applied in multi-DOF vibration reduction platforms in the aerospace field in the modeling process, the least square support vector machine (LS-SVM) method is adopted, because LS-SVM can handle small-sample, high-dimensional characteristic problems. Firstly, the theory of the modeling method based on LS-SVM was illustrated including the genetic algorithm (GA) optimization method. Secondly, the characteristic curve of the MR damper was tested based on different conditions. Then, the current and historical input displacement, velocity, and current and the historical output are taken as the input of the LS-SVM model and the damping force of the current output is taken as the output of the model for model training. Meanwhile, the genetic algorithm is introduced to optimize the parameters of the LS-SVM model which affect the accuracy of the model, the penalty factor c = 16.48 , and the kernel parameter σ = 3.39 after optimization. Finally, in order to verify the method adopted in the paper, the Simulink model was simulated in certain input conditions; by comparing the simulation and experimental values of this model, it is found that the maximum error is within 10 N and the average error is around 0.89 N, which is similar to the accuracy obtained in other works of literature, and the correctness of this model is verified.

The influence of different levels of alkalinity, expressed using M2O-to-binder ratio (n) and activator SiO2-to-M2O ratio (Ms), (M being the Na+ or K+ cation) on the reaction kinetics, compressive strength development and the reaction product formation in slag-based systems activated using alkali powders are discussed. The fundamental idea is to better understand one-part, “just-add-water” type alkali activated binders that are easy-to-use than the systems that rely on liquid activators. The difference in the behavior of the systems with changes in the cationic species (Na+ or K+) and the overall levels of alkalinity is elucidated. Heat release and its rate, and thermal analysis and Fourier Transform Infrared Spectroscopy (FTIR) are used for the characterization of the reaction and the products formed. The influence of activator alkalinity on the initial dissolution and acceleration phases is examined using isothermal calorimetry. An increase in Ms is found to result in reduced early-age and slightly increased later-age compressive strengths. The activator cationic species influences later-age strengths, with K-silicate activated mortars showing a higher strength. The strength data is related to the C-(A)-S-H gel formation. The study shows that slag-based binders can be proportioned to obtained compressive strengths in excess of 80 MPa at later ages (56 days), and up to 30 MPa within 72 hours. The optimal alkali levels based on n and Ms for both the Na- and K-based activator systems are determined.

To deal with the stringent operational demands the aerospace structural materials of light weight Aluminum alloy 2024 sheets and plies of carbon fibers reinforced thermoplastic matrix PEEK were used to sustain at least 80% of their mechanical properties at elevated temperature. The addition of nanoparticles SiO2 can enhance the composite laminate strength and stiffness. Also, Al 2024 sheets were treated by an anodic method of electroplating to increase surface roughness to achieve perfectly bonding with matrix PEEK. Then, the modified diaphragm curing process was adopted to make the innovative hybrid Al/APC-2 hybrid nanocomposite laminates. Next, both static tensile and fatigue tests were conducted at elevated temperature to obtain the mechanical properties, lives and failure mechanisms to verify the improved features of hybrid specimens. From tensile tests the mechanical properties of Al/APC-2 [4Al/0/±45/90/2Al]s hybrid laminates at elevated temperature were obtained. Although there is a big drop at 150°C, the reduction in strength from RT to 125°C is generally not significant. The longitudinal stiffness is almost unchanged at elevated temperature. After cyclic tension-tension (T-T) tests, the positions of received S-N curves go downwards as temperature rising. No delaminations were found in both tests. If the applied stress normalized by the ultimate strength at corresponding temperature, the normalized S-N curves are closer with some curve positions reversed. Significant improvement of manufacturing and enhancement of mechanical properties in hybrid laminates were achieved finally.

The minimization of valve and seat insert wear is a critical factor for consideration in the pursuit of engine performance improvement. In order to achieve this goal, an innovative simulator was developed with the ability to generate and control high temperatures up to 900°C and various frequencies up to 80 Hz during motion, just as in the case of an actual vehicle engine. This wear simulator is considered to be a valid reproduction of the engine valve and seat insert wear process operating with various speeds during engine activity. This work focuses on the different degrees of wear at three different test frequencies (10 Hz, 25 Hz, and multi-hertz). In this study, the seat insert's exterior surface temperature was controlled at 350 °C, the number of cycles was 2.1×106and the test load was 1960 N. The wear depth was measured before and after testing using a confocal laser microscope. It was found that higher frequencies caused a greater degree of wear than lower frequencies under identical test conditions (temperature, valve displacement, number of cycles, and test load). It was intended that an actual vehicle engine be used to perform a similar test, in order that the multi-hertz test, using a combination of the 10 and 25 Hz frequencies be applied. In the wear mechanism, adhesive wear, shear strain, abrasive wear, and surface fatigue wear were observed.

Accurate transport properties of non-ionized gas mixtures of C, H, O, N, and Si-containing species at temperatures up to 4000 K are essential in many scientific fields. Mixture transport properties are computed through the solution of linear transport systems, requiring collision integrals as functions of temperature for each binary collision pair in the mixture. Due to the dimensionality of the problem, no such database exists for all the 180 hydrocarbons and silicon species detailed in the nine-coefficient polynomial thermodynamic database of Gordon and McBride, widely used in many applications. This constraint was overcome by using a phenomenological inter-molecular potential energy surface suitable for transport properties, which describes the pair interaction approximated with two fundamental species physical properties, namely the dipole electric polarizability and the number of effective electrons participating in the interaction. These two parameters were calculated with ab initio quantum chemistry calculations, since they were not always available in literature. The studied methodology was verified and validated against other approaches at a species and collision integral level. Transport properties for a variety of equilibrium mixtures, including planetary atmospheres and chemical compositions of thermal protection materials relevant to aerospace applications, were calculated, assessing the predictive capabilities of this new database.

Creep and stress-rupture properties of cast IN-738LC turbine blades have been analyzed to review the suitability of the Monkman-Grant relationship as a reliable life prediction method where tr ε˙sm = C and m and C are material constants. The constants m and C in the Monkman-Grant relationship are temperature dependent and the relationship predicts lives within a factor of ±4 relative to the observed values. A modified form of this relationship is derived where (−b trn1 + tr) ε˙sm1 = K and b, n, m1, and K are material constants. The modified relationship is more accurate and predicts lives within a factor of 2 relative to the observed values. The constants b, n, m, and k are independent of stress and temperature.

High-temperature-resistant polymeric adhesives with high servicing temperatures and high adhesion strengths are highly desired in aerospace, aviation, microelectronic and other high-tech areas. The currently used high-temperature resistant polymeric adhesives, such as polyamic acid (PAA), are usually made from the high contents of solvents in the composition, which might cause adhesion failure due to the undesirable voids caused by the evaporation of the solvents. In the current work, electrospun preimidized polyimide (PI) nano-fibrous membranes (NFMs) were proposed to be used as solvent-free or solvent-less adhesives for stainless steel adhesion. In order to enhance the adhesion reliability of the PI NFMs, thermally crosslinkable phenylethynyl end-cappers were incorporated into the PIs derived from 3,3’,4,4’-oxydiphthalic anhydride (ODPA) and 3,3-bis[4-(4-aminophenoxy)phenyl]phthalide (BAPPT). The derived phenylethynyl-terminated PETI-10K and PETI-20K with the controlled molecular weights of 10,000 g mol−1 and 20,000 g mol−1, respectively, showed good solubility in polar aprotic solvents, such as N-methyl-2-pyrrolidinone (NMP) and N,N-dimethylacetamide (DMAc). The PI NFMs were successfully fabricated by electrospinning with the PETI/DMAc solutions. The ultrafine PETI NFMs showed the average fiber diameters (dav) of 627 nm for PETI-10K 695 nm for PETI-20K, respectively. The PETI NFMs showed good thermal resistance, which is reflected in the glass transition temperatures (Tgs) above 270 °C. The PETI NFMs exhibited excellent thermoplasticity at elevated temperatures. The stainless steel adherends were successfully adhered using the PETI NFMs as the adhesives. The PI NFMs provided good adhesion to the stainless steels with the single lap shear strengths (LSS) higher than 20.0 MPa either at room temperature (25 °C) or at an elevated temperature (200 °C).

For the research demand of reusable LOX/kerosene variable thrust liquid rocket engine, a test system with electric displacement pumps is designed and a multidisciplinary modular dynamic simulation method based on AMESim platform is used to analyze the system. The method comprehensively considers the characteristics of complex components in the engine and realizes the fast module assembly and variable step size solution. Considering the combustion model of thrust chamber, the positive displacement pump model with complex leakage channels, and the cooling jacket heat transfer model, the component dynamic equations are deduced and the final model simulation results reveal that the system has a smooth ignition, stage turning, and shutdown process. The thrust can reach 6900 N in high working condition and the variable thrust ratio is 5 : 1. The dynamic characteristics of the system show that the performance error of main pump components is less than 5%, the maximum average temperature rise of the thrust chamber coolant is about 28°C, and the time of stage adjustment is within 300 ms, which mean the overall design of the system is reasonable. Although the accumulation of LOX before kerosene injection can adversely affect the temperature of the thrust chamber, large pressure pulses do not occur due to the ignitor’s duty flame. Moreover, the pintle injectors based on PID control can effectively stabilize the pressure drop at lower conditions. The system and the simulation method provide important support for the actual engine test and the general LRE dynamic characteristics analysis.

In this work results are reported from an experimental fatigue programme. The role of the constituent materials upon the fatigue performance of a given composite material system was studied. This involved comparisons of the residual strength, damage development, and in some cases fatigue life. A new method of approach, based upon a unique characteristic fatigue parameter, termed the damage transition stress, St, was also introduced. It has been shown that the employment of the characteristic parameter can simplify the comparison of different material systems considerably. Four graphite reinforced material systems were evaluated: (a) standard epoxy system, (b) toughened epoxy system, (c) thermoplastic system and, (d) high temperature system. It was found that three of the four material systems examined (a, b, and d) were more sensitive to hygrothermal environments, so far as the development of fatigue damage is concerned. In general, the tensile residual strength, in all material systems, showed a marked improvement, whereas the effect of environment and fatigue damage combination upon the compressive strength was more complex. Presentation of the fatigue data in the form of linear S-N plots allowed the determination of St, and its dependence upon environment and material systems. A material dynamic toughness was also identified.

Abstract Polyimides are a sophisticated family of materials, which cover an exhaustive range of high performance polymers and find applications from aerospace to microelectronics. Microelectronic applications demand low dielectric constant and high performance. Aromatic terpolyimides were synthesized by reacting 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) with 4,4′-oxydianiline (ODA) by thermal imidization with the view to decrease their dielectric constant without compromising thermal properties and mechanical properties compared to their homo and copolyimides. They were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Their FTIR spectra established formation of polyimide by the characteristic vibrations at 1375 cm-1 (C-N stretch) and 1113 cm-1 (imide ring deformation). The TGA results showed decomposition of imides at about 515°C. The glass transition temperature (Tg) of the polymers varied from 261°C to 281°C. The XRD spectrum of BPDA/BTDA/6FDA-ODA, which contained 50% of 6FDA, showed a broadened envelope with a peak at 16.8° (2θ), illustrating a semicrystalline nature. Incorporation of 6FDA, with a bulky bridging group into the backbone of BPDA/6FDA-ODA and BPDA/BTDA/6FDA-ODA (0.25:0.25:0.5::1) caused a decrease in the dielectric constant (2.13 and 2.38, respectively). Such polyimides can find application in microelectronics such as flexible printed circuits and tape automated bonding applications.

A high-speed and high-temperature calorimetric solid-state thermal mass flow sensor (TMFS) design was proposed and its sensitivity to temperature and airflow speed were numerically assessed. The sensor operates at 573.15 Kelvin (300 °C), measuring speeds up to 265 m/s, and is customized to be a transducer for an aircraft Air Data System (ADS). The aim was to enhance the system reliability against ice accretion on pitot tubes’ pressure intakes, which causes the system to be inoperative and the aircraft to lose protections that ensure its safe operation. In this paper, the authors assess how the distance between heater and thermal sensors affects the overall TMFS sensitivity and how it can benefit from the inclusion of a thermal barrier between these elements. The results show that, by increasing the distance between the heater and temperature sensors from 0.1 to 0.6 mm, the sensitivity to temperature variation is improved by up to 80%, and that to airspeed variation is improved by up to 100%. In addition, adding a thermal barrier made of Parylene-N improves it even further, by nearly 6 times, for both temperature and air speed variations.

Brazed joints were made between silicon nitride and Ni-based and Fe-based super alloys. Room temperature shear (torsion) strengths ranged from 75-242 MPa for Si3N4-to-Incoloy 909 joints and from 30-127 MPa for the Si3N4-to-Inconel 718 joints. At 500°C the joint strength was 120 MPa while at 650°C and 950°C the joint strengths were less than 20 MPa. These low strengths at 650°C and 950°C were attributed to a reduction in the shrink-fit and to low braze strength at these high temperatures. Finite element analysis (FEA) and a probabilistic failure theory (CARES) were used to predict the joint strengths. The predicted joint strengths agreed well with measured joint strengths in torsional loading at 20°C. Torsion tests were also performed at 650°C. Aspects of the material systems, residual stresses, mechanical behavior, and strength predictions and presented. Two new braze alloys based on the Au-Ni-Cr-Fe system were used to overcome the poor high-temperature strength. Joints made with these brazes had good strength (85 MPa and 35 N-m) at 650°C.

In the present work by employing the Technique for order of preference by similarity to ideal solution (TOPSIS) machining parameters optimization is performed with polycrystalline cubic boron nitride (PCBN) tools while AISI 52100 steel hard turning (HT). Based on the CCD of RSM, 32 experimental runs were performed by varying cutting speed, feed, depth of cut, nose radius, and negative rake angle to identify the optimal level of the process parameters. In this study, the multiple performance characteristics measured are machining force, surface roughness, and workpiece surface temperature. To ascertain the impact of cutting parameters on responses, Analysis of Variance (ANOVA) was deployed. An optimum combination of input process parameters for the multiple performance characteristics should be as follows: speed 200 rpm, feed 0.1 mm/rev, depth of cut 0.8 mm, nose radius 1.2 mm, and negative rake angle 45º leading to the value of optimum response variables machining force 561.163 N, Surface roughness 0.507μm and workpiece surface temperature 84.38°C.

Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000°F (538°C) and rotor speeds to 15,000 rpm along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core circuit using 22A was 600 lb (2.67 kN) at room temperature and 380 lb (1.69 kN) at 538°C. These values were compared with force predictions based on a one-dimensional magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. The analysis showed that the reduction of force at high temperature is mostly due to an increase in radial gap due to test conditions, rather than to reduced core permeability. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing’s static force capacity. One C-core required approximately 340 W of power to generate 190 lb (845 N) of magnetic force at 538°C, however the magnetic air gap was much larger than at room temperature. The data presented are after bearing operation for eleven total hours at 538°C and six thermal cycles.

The fiber laminate composites are extensively used in aerospace, aircraft, automotive components due to their high stiffness, corrosion, moisture resistance, low weight, and durability features. These fiber composites are modified with nanomaterials to acquire the desired manufacturing properties. The complex structure and anisotropic features differ from metals and their alloys. Additionally, the machining principles of fiber laminates significantly differ from conventional engineering materials. The present work investigates the machining behavior and permeates the damage generated while milling of graphene-modified carbon-fiber reinforced polymer nanocomposites (G/C@FRNC). The surface damages and defects caused in the milling samples have been examined through the high-resolution spectroscopy test. The influence of machining constraints such as cutting speed (N), feed rate (F), depth of cut (D), and graphene oxide weight % (GO) has been investigated to achieve the desired milling performances viz. material removal rate (MRR), cutting force (Fc), surface roughness (Ra), and delamination factor (Fd). The outcomes indicated that the cutting parameters and graphene nanomaterial prominently affects the milling responses. The addition of graphene improves the machinability of proposed nanocomposites with lesser defects generated. However, its higher addition can lead to the phenomenon of agglomeration that can reduce the machining efficiency. The damages and delamination generated in the machined sample are low at a higher cutting speed. This work suggests a new system to control the damage and defects to enhance the laminate samples’ quality and productivity.

Many aerospace industrial applications require robust and efficient numerical solutions of large sparse nonlinear constrained parameter optimization problems arising from optimal trajectory problems. A three-dimensional multistage launcher problem is taken as a numerical example for studying the performance and applicability of the full-space Lagrange–Newton–Krylov method. The typical optimal trajectory, control history and other important physical qualities are presented, and the efficiency of the algorithm is also investigated. References J. T. Betts. Practical methods for optimal control and estimation using nonlinear programming. Advances in Design and Control. SIAM, 2nd edition, 2010. doi:10.1137/1.9780898718577. R. T. Marler and J. S. Arora. Survey of multi-objective optimization methods for engineering. Struct. Multidiscip. Opt., 26(6):369395, 2004. doi:10.1007/s00158-003-0368-6. W. Roh and Y. Kim. Trajectory optimization for a multi-stage launch vehicle using time finite element and direct collocation methods. Eng. Opt., 34:1532, 2002. doi:10.1080/03052150210912. G. D. Silveira and V. Carrara. A six degrees-of-freedom flight dynamics simulation tool of launch vehicles. J. Aero. Tech. Manag., 7:231239, 2015. doi:10.5028/jatm.v7i2.433. H.-H. Wang, Y.-S. Lo, F.-T. Hwang, and F.-N. Hwang. A full-space quasi-LagrangeNewtonKrylov algorithm for trajectory optimization problems. Electron. T. Numer. Anal., 49:103125, 2018. doi:10.1553/etna_vol49s103. H. Yang, F.-N. Hwang, and X.-C. Cai. Nonlinear preconditioning techniques for full-space Lagrange-Newton solution of PDE-constrained optimization problems. SIAM J. Sci. Comput., 38:A2756A2778, 2016. doi:10.1137/15M104075X.

The 7020-aluminum alloy is a lightweight and high strength material which is widely used in aerospace industries where the damage tolerance, the factor of safety and environmental induced fatigue is very high. The low density and better mechanical properties enable its applications in industries over conventional engineering materials. In the present work, the fatigue crack growth (FCG) behavior of the pre-corroded 7020-aluminum alloy was investigated. The samples were subjected to an aqueous solution of sodium chloride; the micro-hardness was optimized and the significance of corrosion on FCG was studied in the context of bending stress, the number of cycles (N) to failure/fatigue life and microstructure. The solution treated samples at a temperature of 520°C for 3 hours provided the maximum hardness. However, the hardness of samples was optimum for 3 hours of solution heat treatment and minimum for 2 hours of solution heat treatment. It is suggested that the precipitation of the metastable phase affected the hardness. In the initial stage, the fatigue life of pre-corroded samples was significantly lower as compared to as-received samples. However, at the later stage, it became less significant but still, the pre-corroded sample showed lower fatigue life. Both types (pre-corroded and as-received) of samples showed a similar trend as fatigue life decreases with increasing bending stress. The fractured microstructure of the pre-corroded sample showed scratches on the surface which were produced during mechanical rubbing of the specimen pieces during plastic deformation under load. However, the microstructure at the edge of the notch showed "volcano-mouth" features" which indicated the phenomena of galvanic corrosion. The galvanic corrosion envisages due to deposition on the 7020-aluminum alloy and the impurities in the alloy. The elements Fe, Si, C and Mn existed as impurities that induced the galvanic corrosion and an elliptical corrosion pit was observed.

Unexpectedly high concentrations of NO2 formation have been noted in stack emissions from industrial combustors. NO2 formation has been reported to occur through the so-called “HO2 mechanism” in which NO combines with HO2 to produce NO2 and OH In this study, the formation of NO2 was investigated at superatmospheric pressures through experiments and computer modeling. Computer modeling utilized the CHEMKIN chemical kinetics program and a subset of a previously published C–H–O–N system mechanism. Experimental work was conducted using a high-pressure flow reactor designed and built in the course of the study. The effects of pressure, temperature, and the presence of a NO2-promoting hydrocarbon, methane, were investigated. It was discovered that as pressure increased from 1 atm to 8.5 atm, the rate and amount of NO converted to NO2 also increased. The results also show a temperature “window” between approximately 800 K and 1000 K in which NO to NO2 conversion readily occurred. The presence of methane was seen to enhance NO conversion to NO2, and a ratio of [CH4]/[NO] was found to be a useful parameter in predicting NO2 formation. Significant NO conversion to NO2 was noted for [CH4]/[NO] > 1 at the hydrocarbon injection point. Experimental results validated those trends obtained from modeling with a modified C–H–O–N mechanism.

Air bearing has been widely applied in ultra-precision machine tools, aerospace and other fields. The restrictor of the porous material is the key component in air bearings, but its performance is limited by the machining accuracy. A combination of optimization design and material modification of the porous alumina ceramic membrane is proposed to improve performance within an air bearing. Porous alumina ceramics were prepared by adding a pore-forming agent and performing solid-phase sintering at 1600 °C for 3 h, using 95-Al2O3 as raw material and polystyrene microspheres with different particle sizes as the pore-forming agent. With 20 wt.% of PS50, the optimum porous alumina ceramic membranes achieved a density of 3.2 g/cm3, a porosity of 11.8% and a bending strength of 150.4 MPa. Then, the sintered samples were processed into restrictors with a diameter of 40 mm and a thickness of 5 mm. After the restrictors were bonded to aluminum shells for the air bearing, both experimental and simulation work was carried out to verify the designed air bearing. Simulation results showed that the load capacity increased from 94 N to 523 N when the porosity increased from 5% to 25% at a fixed gas supply pressure of 0.5 MPa and a fixed gas film thickness of 25 μm. When the gas film thickness and porosity were fixed at 100 μm and 11.8%, respectively, the load capacity increased from 8.6 N to 40.8 N with the gas supply pressure having been increased from 0.1 MPa to 0.5 MPa. Both experimental and simulation results successfully demonstrated the stability and effectiveness of the proposed method. The porosity is an important factor for improving the performance of an air bearing, and it can be optimized to enhance the bearing’s stability and load capacity.

The objective of this work is to investigate the effects of environmental conditions on the axial fatigue behavior of a carbon/epoxy plain-weave laminate with an embedded flaw subjected to a partially reversed cyclic load (stress ratio R = −0.1) in tension–compression. This specific material is more commonly used in aerospace engineering for the manufacturing of aircraft structural parts, which are directly exposed to various environmental conditions during service. Specific environmental and loading conditions that are appropriate to simulate real-life conditions are considered to observe and collect information about the material's behavior. For the investigation, dry and wet coupons were submitted to room temperature, 82 and 121 ℃ under loading frequencies of 7 and 15 Hz. A maximum allowable strain increase criterion is used to monitor the flaw growth threshold or delamination onset, during fatigue testing. The ultrasonic imaging (C-scan) technique is used to verify and confirm the delamination onset. Results show that the delamination onset strain increase criterion, along with fatigue life, generally decreased as the operating temperature and humidity were increased and that frequency had little effect on the delamination onset fatigue life. The S– N curves obtained from the tension–compression fatigue data were then compared to those of a previous work carried out in tension–tension fatigue loading. Results show a clear degradation in the delamination onset fatigue life of the coupons tested under tension–tension cyclic loading when the minimum tensile component of the cyclic load was replaced with a compressive load of the same magnitude.

PurposeThe purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.Design/methodology/approachHere, a very detailed evaluation on the stereochemistry of two new ruthenium catalysts evidences the crucial role of the spatial orientation of phenyl groups in the N-heterocyclic carbene ligands in determining the temperature range within the curing cycles is feasible without deactivating the self-healing mechanisms (ring-opening metathesis polymerization reactions) inside the thermosetting resin. The exceptional activity and thermal stability of the HG2MesPhSyncatalyst, with the syn orientation of phenyl groups, highlight the relevant potentiality and the future perspectives of this complex for the activation of the self-healing function in aeronautical resins.FindingsThe HG2MesPhSyncomplex, with the syn orientation of the phenyl groups, is able to activate metathesis reactions within the highly reactive environment of the epoxy thermosetting resins, cured up to 180°C, while the other stereoisomer, with the anti-orientation of the phenyl groups, does not preserve its catalytic activity in these conditions.Originality/valueIn this paper, a comparison between the self-healing functionality of two catalytic systems has been performed, using metathesis tests and FTIR spectroscopy. In the field of the design of catalytic systems for self-healing structural materials, a very relevant result has been found: a slight difference in the molecular stereochemistry plays a key role in the development of self-healing materials for aeronautical and aerospace applications.

Abstract Renewable resources are used to create useful, biologically sustainable materials. It has the potential to minimize waste while also challenging existing research and developments. Several researchers have concentrated their efforts on natural fiber composites. Natural fibers include plant, mineral, and animal fibers. In this project fish scales, a bio-waste, were used as a reinforcing agent in polyester/polystyrene for the fabrication of composite materials in the different weight fractions of 0, 6, 7, 9, and 11%, at a constant load of 1 N and temperature of 20 and 26°C. The hand layup technique was used to create the fabrication setup for composite materials. The creep behavior, modulus of elasticity, and stress were studied experimentally.

In recent times, tribological properties are gaining and grabbing great attention in metal matrix composites. They can provide significant benefits such as a lower coefficient of friction, wear resistance, high strength, and stiffness. Considering all these parameters, this research article mainly focuses on developing an aluminum hybrid nanocomposite material fabricated by powder metallurgy. Then, the results were examined using a pin-on-disk apparatus. Further optimization techniques such as the Taguchi approach under Design of Experiments have been adopted to obtain a minimal outcome of various assumed parameters such as A. percentage weight fraction of graphite content (Gr), B. the sliding distance, C. the sliding speed, and D. the stress applied. In addition, we have chosen parameters such as friction and wear loss for optimizing the outcome, including the main effect plots for the S-N ratio and the Analysis of Variance (ANOVA) approach. Based on the experimental results, we have noticed that friction and wear loss coefficient increase with increased applied load and sliding distance. Also, it was noted that there was a slight decrease in the coefficient of friction and wear loss when an increment was made in the graphite content, respectively. It was perceived that the sample containing 10% of graphite (Gr) could create a self-lubricating effect that significantly reduced wear loss and the coefficient of friction. Finally, by considering all these achieved results, aluminum nanocomposites can be employed in automobile, defense, and aerospace applications as they can reduce the weight of the components with improved wear behavior and more thermal stability.

In 2013 the Editor of Journal of Vibration and Control and SAGE became aware of a peer review ring involving assumed and fabricated identities that appeared to centre around Peter Chen at National Pingtung University of Education, Taiwan (NPUE). SAGE and the Editor then began a complex investigation into the case during the rest of 2013 and 2014. Following an unsatisfactory response from Peter Chen, NPUE was notified. NPUE were serious in addressing the Journal and SAGE’s concerns. NPUE confirmed that the institution was investigating Peter Chen. SAGE subsequently uncovered a citation ring involving the above mentioned author and others. We regret that individual authors have compromised the academic record by perverting the peer review process and apologise to readers. On uncovering problems with peer review and citation SAGE immediately put steps in place to avoid similar vulnerability of the Journal to exploitation in the future. More information may be found at www.sagepub.co.uk/JVC_Statement_2014 . The Journal and SAGE understand from NPUE that Peter Chen has resigned his post at NPUE. The following articles are retracted because after thorough investigation evidence points towards them having at least one author or being reviewed by at least one reviewer who has been implicated in the peer review ring and/or citation ring. All authors have had an opportunity to respond to the allegations and proposed actions. OnlineFirst articles (these articles will not be published in an issue) Chen CY, Chen T-H, Chen Y-H, Yu S-E and Chung P-Y (2013) Information technology system modeling an integrated C-TAM-TPB model to the validation of ocean tidal analyses Journal of Vibration and Control Epub ahead of print 7 May 2013. doi: 10.1177/1077546312472924 Chang R-F, Chen CY, Su F-P and Lin H-C (2013) A two-step approach for broadband digital signal processing technique Journal of Vibration and Control Epub ahead of print 26 April 2013. doi: 10.1177/1077546312472925 Chen TH, Chang CJ, Yu SE, Chung PY and Liu C-K (2013) Nonlinear information analysis and system management technique: the influence of design experience and control complexity Journal of Vibration and Control Epub ahead of print 12 April 2013. doi: 10.1177/1077546312473321 Chen CY, Shih BY, Chen YH, Yu SE and Liu YC (2013) The exploration of a 3T flow model using vibrating NXT: II. Model validation Journal of Vibration and Control Epub ahead of print 10 April 2013. doi: 10.1177/1077546312470481 Chen CY, Shih BY, Chen YH, Yu SE and Liu YC (2013) The exploration of 3T flow model using vibrating NXT: I. model formulation Journal of Vibration and Control Epub ahead of print 6 February 2013. doi: 10.1177/1077546312467360 Lin M-L and Chen C-W (2013) Stability analysis of fuzzy-based NN modeling for ecosystems using fuzzy Lyapunov methods Journal of Vibration and Control Epub ahead of print 6 February 2013. doi: 10.1177/1077546312466687 Chen CY, Chen TH, Chen YH and Chiu J (2012) A multi-stage method for deterministic-statistical analysis: a mathematical case and measurement studies Journal of Vibration and Control Epub ahead of print 20 December 2012. doi: 10.1177/1077546312466579 Shih BY, Lin MC and Chen CY (2012) Autonomous navigation system for radiofrequency identification mobile robot e-book reader Journal of Vibration and Control Epub ahead of print 13 December 2012. doi: 10.1177/1077546312466578 Chang RF, Chen CY, Su FP, Lin HC and Lu C-K (2012) Multiphase SUMO robot based on an agile modeling-driven process for a small mobile robot Journal of Vibration and Control Epub ahead of print 13 December 2012. doi: 10.1177/1077546312464993 Shih B-Y, Lin Y-K, Cheng M-H, Chen C-Y and Chiu C-P (2012) The development of an application program interactive game-based information system Journal of Vibration and Control Epub ahead of print 12 December 2012. doi: 10.1177/1077546312464682 Chen C-Y, Chang C-J and Lin C-H (2012) On dynamic access control in web 2.0 and cloud interactive information hub: technologies Journal of Vibration and Control Epub ahead of print 12 December 2012. doi: 10.1177/1077546312464992 Shin BY, Chen CY and Hsu KH (2012) Robot cross platform system using innovative interactive theory and selection algorithms for Android application Journal of Vibration and Control Epub ahead of print 13 November 2012. doi: 10.1177/1077546312463757 Articles published in an issue Chen C-W (2014) Applications of neural-network-based fuzzy logic control to a nonlinear time-delay chaotic system Journal of Vibration and Control 20 (4): 589-605. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312461370 Chen C-W (2014) A review of intelligent algorithm approaches and neural-fuzzy stability criteria for time-delay tension leg platform systems Journal of Vibration and Control 20 (4): 561-575. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312463759 Chen C-Y, Chang C-J and Lin C-H (2014) On dynamic access control in web 2.0 and cloud interactive information hub: trends and theories Journal of Vibration and Control 20 (4): 548-560. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312463762 Lin M-L and Chen C-W (2014) Stability conditions for ecosystem modeling using the fuzzy Lyapunov method Journal of Vibration and Control 20 (2): 290-302. Epub ahead of print 23 October 2012. doi: 10.1177/1077546312451301 Chen C-H, Kuo C-M, Hsieh S-H and Chen C-Y (2014) Highly efficient very-large-scale integration (VLSI) implementation of probabilistic neural network image interpolator Journal of Vibration and Control 20 (2): 218-224. Epub ahead of print 22 October 2012. doi: 10.1177/1077546312458822 Chen C-Y (2014) Wave vibration and simulation in dissipative media described by irregular boundary surfaces: a mathematical formulation Journal of Vibration and Control 20 (2): 191-203. Epub ahead of print 22 October 2012. doi: 10.1177/1077546312464258 Chen C-H, Yao T-K, Dai J-H and Chen C-Y (2014) A pipelined multiprocessor system- on-a-chip (SoC) design methodology for streaming signal processing Journal of Vibration and Control 20 (2): 163-178. Epub ahead of print 16 October 2012. doi: 10.1177/1077546312458821 Lin M-L and Chen C-W (2014) Fuzzy neural modeling for n-degree ecosystems using the linear matrix inequality approach Journal of Vibration and Control 20 (1): 82-93. Epub ahead of print 8 October 2012. doi: 10.1177/1077546312458533 Chen C-H, Wu W-X and Chen C-Y (2013) Ant-inspired collective problem-solving systems Journal of Vibration and Control 19 (16): 2481-2490. Epub ahead of print 18 September 2012. doi: 10.1177/1077546312456231 Chen C-H, Yao T-K, Kuo C-M and Chen C-Y (2013) Evolutionary design of constructive multilayer feedforward neural network Journal of Vibration and Control 19 (16): 2413-2420. Epub ahead of print 12 September 2012. doi: 10.1177/1077546312456726 Chen C-W (2013) Applications of the fuzzy-neural Lyapunov criterion to multiple time-delay systems Journal of Vibration and Control 19 (13): 2054-2067. Epub ahead of print 16 August 2012. doi: 10.1177/1077546312451034 Chung P-Y, Chen Y-H, Walter L and Chen C-Y (2013) Influence and dynamics of a mobile robot control on mechanical components Journal of Vibration and Control 19 (13): 1923-1935. Epub ahead of print 20 July 2012. doi: 10.1177/1077546312452184 Chen C-W (2013) Neural network-based fuzzy logic parallel distributed compensation controller for structural system Journal of Vibration and Control 19 (11): 1709-1727. Epub ahead of print 22 June 2012. doi: 10.1177/1077546312442233 Chen C-W, Yeh K, Yang H-C, Liu KFR and Liu C-C (2013) A critical review of structural system control by the large-scaled neural network linear-deferential-inclusion-based criterion Journal of Vibration and Control 19 (11): 1658-1673. Epub ahead of print 18 June 2012. doi: 10.1177/1077546312443377 Chen C-H, Kuo C-M, Chen C-Y and Dai J-H (2013) The design and synthesis using hierarchical robotic discrete-event modeling Journal of Vibration and Control 19 (11): 1603-1613. Epub ahead of print 27 June 2012. doi: 10.1177/1077546312449645 Chang CJ, Chen CY and Chou I-T (2013) The design of information and communication technologies: telecom MOD strength machines Journal of Vibration and Control 19 (10): 1499-1513. Epub ahead of print 27 June 2012. doi: 10.1177/1077546312449644 Shih B-Y, Chen C-Y, Li K-H, Wu T-Y, Chen G-Y (2013) A novel NXT control method for implementing force sensing and recycling in a training robot Journal of Vibration and Control 19 (10): 1443-1459. Epub ahead of print 1 June 2012. doi: 10.1177/1077546312446361 Chen C-W, Chen P-C and Chiang W-L (2013) Modified intelligent genetic algorithm-based adaptive neural network control for uncertain structural systems Journal of Vibration and Control 19 (9): 1333-1347. Epub ahead of print 31 May 2012. doi: 10.1177/1077546312442232 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Enhancing robust and stability control of a humanoid biped robot: system identification approach. Journal of Vibration and Control 19 (8): 1199-1207. Epub ahead of print 26 April 2012. doi: 10.1177/1077546312442947 Chang C-J, Chen C-Y and Huang C-W (2013) Applications for medical recovery using wireless control of a bluetooth ball with a hybrid G-sensor and human-computer interface technology Journal of Vibration and Control 19 (8): 1139-1151. Epub ahead of print 24 April 2012. doi: 10.1177/1077546312442948 Hsu W-K, Chiou D-J, Chen C-W, Liu M-Y, Chiang W-L and Huang P-C (2013) Sensitivity of initial damage detection for steel structures using the Hilbert-Huang transform method Journal of Vibration and Control 19 (6): 857-878. Epub ahead of print 29 February 2012. doi: 10.1177/1077546311434794 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Human–machine interface for the motion control of humanoid biped robots using a graphical user interface Motion Editor Journal of Vibration and Control 19 (6): 814-820. Epub ahead of print 23 February 2012. doi: 10.1177/1077546312437804 Chen C-Y (2013) Internal wave transport, nonlinear manifestation, and mixing in a stratified shear layer - technical briefs Journal of Vibration and Control 19 (3): 429-438. Epub ahead of print 18 January 2012. doi: 10.1177/1077546311429337 Chen C-W (2013) Delay independent criterion for multiple time-delay systems and its application in building structure control systems Journal of Vibration and Control 19 (3): 395-414. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429341 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Design, modeling and stability control for an actuated dynamic walking planar bipedal robot Journal of Vibration and Control 19 (3): 376-384. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429476 Liu K-C, Liu Y-W, Chen C-Y and Huang W-C (2013) Nonlinear vibration of structural deterioration in reinforced concrete columns: experimental and theoretical investigation Journal of Vibration and Control 19 (3): 323-335. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429477 Chen C-Y, Shih B-Y and Ma J-m (2013) Development for low-cost and cross-platform robot control environment Journal of Vibration and Control 19 (2): 228-233. Epub ahead of print 11 January 2012. doi: 10.1177/1077546311430107 Shih B-Y, Chang H and Chen C-Y (2013) Path planning for autonomous robots – a comprehensive analysis by a greedy algorithm Journal of Vibration and Control 19 (1): 130-142. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429841 Liu T-Y, Chiang W-L, Chen C-W, Hsu W-K, Lin C-W, Chiou D-J and Huang P-C (2012) Structural system identification for vibration bridges using the Hilbert–Huang transform Journal of Vibration and Control 18 (13): 1939-1956. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428347 Chen C-W (2012) Applications of the fuzzy Lyapunov linear matrix inequality criterion to a chaotic structural system Journal of Vibration and Control 18 (13): 1925-1938. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428346 Chen C-W (2012) Applications of linear differential inclusion-based criterion to a nonlinear chaotic system: a critical review Journal of Vibration and Control 18 (12): 1886-1899. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428345 Shih B-Y, Chen C-Y and Chou W (2012) An enhanced obstacle avoidance and path correction mechanism for an autonomous intelligent robot with multiple sensors Journal of Vibration and Control 18 (12): 1855-1864. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311426734 Chen C-W, Yeh K, Liu KFR and Lin M-L (2012) Applications of fuzzy control to nonlinear time-delay systems using the linear matrix inequality fuzzy Lyapunov method Journal of Vibration and Control 18 (10): 1561-1574. Epub ahead of print 18 October 2011. doi: 10.1177/1077546311410765 Chen C-Y (2012) A critical review of internal wave dynamics. Part 2 – Laboratory experiments and theoretical physics Journal of Vibration and Control 18 (7): 983-1008. Epub ahead of print 21 September 2011. doi: 10.1177/1077546310397561 Chen C-Y and Huang P-H (2012) Review of an autonomous humanoid robot and its mechanical control Journal of Vibration and Control 18 (7): 973-982. Epub ahead of print 21 September 2011. doi: 10.1177/1077546310395974 Shih B-Y, Chen C-Y, Chang H and Ma J-m (2012) Dynamics and control for robotic manipulators using a greedy algorithm approach Journal of Vibration and Control 18 (6): 859-866. Epub ahead of print 25 August 2011. doi: 10.1177/1077546311407649 Yeh K, Chen C-W, Lo DC and Liu KFR (2012) Neural-network fuzzy control for chaotic tuned mass damper systems with time delays Journal of Vibration and Control 18 (6): 785-795. Epub ahead of print 15 August 2011. doi: 10.1177/1077546311407538 Chen C-Y, Shih B-Y, Shih C-H and Chou W-C (2012) The development of autonomous low-cost biped mobile surveillance robot by intelligent bricks Journal of Vibration and Control 18 (5): 577-586. Epub ahead of print 21 April 2011. doi: 10.1177/1077546310371349 Chen C-Y (2012) A critical review of internal wave dynamics. Part 1 – Remote sensing and in-situ observations Journal of Vibration and Control 18 (3): 417-436. Epub ahead of print 13 July 2011. doi: 10.1177/1077546310395971 Tseng C-P, Chen C-W and Liu KFR (2012) Risk control allocation model for pressure vessels and piping project Journal of Vibration and Control 18 (3): 385-394. Epub ahead of print 13 July 2011. doi: 10.1177/1077546311403182 Lin M-L and Chen C-W (2011) Stability analysis of community and ecosystem hierarchies using the Lyapunov method Journal of Vibration and Control 17 (13): 1930-1937. Epub ahead of print 9 December 2010. doi: 10.1177/1077546310385737 Chen C-Y, Shih B-Y, Chou W-C, Li Y-J and Chen Y-H (2011) Obstacle avoidance design for a humanoid intelligent robot with ultrasonic sensors Journal of Vibration and Control 17 (12): 1798-1804. Epub ahead of print 26 November 2010. doi: 10.1177/1077546310381101 Chen C-W (2011) Fuzzy control of interconnected structural systems using the fuzzy Lyapunov method Journal of Vibration and Control 17 (11): 1693-1702. Epub ahead of print 23 November 2010. doi: 10.1177/1077546310379625 Shih B-Y, Chen C-Y and Chou W-C (2011) Obstacle avoidance using a path correction method for autonomous control of a biped intelligent robot Journal of Vibration and Control 17 (10): 1567-1573. Epub ahead of print 22 November 2010. doi: 10.1177/1077546310372004 Tang J-P, Chiou D-J, Chen C-W, Chiang W-L, Hsu W-K, Chen C-Y and Liu T-Y (2011) A case study of damage detection in benchmark buildings using a Hilbert-Huang Transform-based method Journal of Vibration and Control 17 (4): 623-636. Epub ahead of print 8 November 2010. doi: 10.1177/1077546309360053 Liu TY, Chiang WL, Chen CW, Hsu WK, Lu LC and Chu TJ (2011) Identification and monitoring of bridge health from ambient vibration data Journal of Vibration and Control 17 (4): 589-603. Epub ahead of print 12 November 2010. doi: 10.1177/1077546309360049 Lin JW, Huang CW, Shih CH and Chen CY (2011) Fuzzy Lyapunov Stability Analysis and NN Modeling for Tension Leg Platform Systems Journal of Vibration and Control 17 (1): 151-158. Epub ahead of print 25 August 2010. doi: 10.1177/1077546309350477 Lee WI, Chen CY, Kuo HM and Sui YC (2010) The Development of Half-circle Fuzzy Numbers and Application in Fuzzy Control Journal of Vibration and Control 16 (13): 1977-1987. Epub ahead of print 22 April 2010. doi: 10.1177/1077546309349849

In 2013 the Editor of Journal of Vibration and Control and SAGE became aware of a peer review ring involving assumed and fabricated identities that appeared to centre around Peter Chen at National Pingtung University of Education, Taiwan (NPUE). SAGE and the Editor then began a complex investigation into the case during the rest of 2013 and 2014. Following an unsatisfactory response from Peter Chen, NPUE was notified. NPUE were serious in addressing the Journal and SAGE’s concerns. NPUE confirmed that the institution was investigating Peter Chen. SAGE subsequently uncovered a citation ring involving the above mentioned author and others. We regret that individual authors have compromised the academic record by perverting the peer review process and apologise to readers. On uncovering problems with peer review and citation SAGE immediately put steps in place to avoid similar vulnerability of the Journal to exploitation in the future. More information may be found at www.sagepub.co.uk/JVC_Statement_2014 . The Journal and SAGE understand from NPUE that Peter Chen has resigned his post at NPUE. The following articles are retracted because after thorough investigation evidence points towards them having at least one author or being reviewed by at least one reviewer who has been implicated in the peer review ring and/or citation ring. All authors have had an opportunity to respond to the allegations and proposed actions. OnlineFirst articles (these articles will not be published in an issue) Chen CY, Chen T-H, Chen Y-H, Yu S-E and Chung P-Y (2013) Information technology system modeling an integrated C-TAM-TPB model to the validation of ocean tidal analyses Journal of Vibration and Control Epub ahead of print 7 May 2013. doi: 10.1177/1077546312472924 Chang R-F, Chen CY, Su F-P and Lin H-C (2013) A two-step approach for broadband digital signal processing technique Journal of Vibration and Control Epub ahead of print 26 April 2013. doi: 10.1177/1077546312472925 Chen TH, Chang CJ, Yu SE, Chung PY and Liu C-K (2013) Nonlinear information analysis and system management technique: the influence of design experience and control complexity Journal of Vibration and Control Epub ahead of print 12 April 2013. doi: 10.1177/1077546312473321 Chen CY, Shih BY, Chen YH, Yu SE and Liu YC (2013) The exploration of a 3T flow model using vibrating NXT: II. Model validation Journal of Vibration and Control Epub ahead of print 10 April 2013. doi: 10.1177/1077546312470481 Chen CY, Shih BY, Chen YH, Yu SE and Liu YC (2013) The exploration of 3T flow model using vibrating NXT: I. model formulation Journal of Vibration and Control Epub ahead of print 6 February 2013. doi: 10.1177/1077546312467360 Lin M-L and Chen C-W (2013) Stability analysis of fuzzy-based NN modeling for ecosystems using fuzzy Lyapunov methods Journal of Vibration and Control Epub ahead of print 6 February 2013. doi: 10.1177/1077546312466687 Chen CY, Chen TH, Chen YH and Chiu J (2012) A multi-stage method for deterministic-statistical analysis: a mathematical case and measurement studies Journal of Vibration and Control Epub ahead of print 20 December 2012. doi: 10.1177/1077546312466579 Shih BY, Lin MC and Chen CY (2012) Autonomous navigation system for radiofrequency identification mobile robot e-book reader Journal of Vibration and Control Epub ahead of print 13 December 2012. doi: 10.1177/1077546312466578 Chang RF, Chen CY, Su FP, Lin HC and Lu C-K (2012) Multiphase SUMO robot based on an agile modeling-driven process for a small mobile robot Journal of Vibration and Control Epub ahead of print 13 December 2012. doi: 10.1177/1077546312464993 Shih B-Y, Lin Y-K, Cheng M-H, Chen C-Y and Chiu C-P (2012) The development of an application program interactive game-based information system Journal of Vibration and Control Epub ahead of print 12 December 2012. doi: 10.1177/1077546312464682 Chen C-Y, Chang C-J and Lin C-H (2012) On dynamic access control in web 2.0 and cloud interactive information hub: technologies Journal of Vibration and Control Epub ahead of print 12 December 2012. doi: 10.1177/1077546312464992 Shin BY, Chen CY and Hsu KH (2012) Robot cross platform system using innovative interactive theory and selection algorithms for Android application Journal of Vibration and Control Epub ahead of print 13 November 2012. doi: 10.1177/1077546312463757 Articles published in an issue Chen C-W (2014) Applications of neural-network-based fuzzy logic control to a nonlinear time-delay chaotic system Journal of Vibration and Control 20 (4): 589-605. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312461370 Chen C-W (2014) A review of intelligent algorithm approaches and neural-fuzzy stability criteria for time-delay tension leg platform systems Journal of Vibration and Control 20 (4): 561-575. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312463759 Chen C-Y, Chang C-J and Lin C-H (2014) On dynamic access control in web 2.0 and cloud interactive information hub: trends and theories Journal of Vibration and Control 20 (4): 548-560. Epub ahead of print 5 November 2012. doi: 10.1177/1077546312463762 Lin M-L and Chen C-W (2014) Stability conditions for ecosystem modeling using the fuzzy Lyapunov method Journal of Vibration and Control 20 (2): 290-302. Epub ahead of print 23 October 2012. doi: 10.1177/1077546312451301 Chen C-H, Kuo C-M, Hsieh S-H and Chen C-Y (2014) Highly efficient very-large-scale integration (VLSI) implementation of probabilistic neural network image interpolator Journal of Vibration and Control 20 (2): 218-224. Epub ahead of print 22 October 2012. doi: 10.1177/1077546312458822 Chen C-Y (2014) Wave vibration and simulation in dissipative media described by irregular boundary surfaces: a mathematical formulation Journal of Vibration and Control 20 (2): 191-203. Epub ahead of print 22 October 2012. doi: 10.1177/1077546312464258 Chen C-H, Yao T-K, Dai J-H and Chen C-Y (2014) A pipelined multiprocessor system- on-a-chip (SoC) design methodology for streaming signal processing Journal of Vibration and Control 20 (2): 163-178. Epub ahead of print 16 October 2012. doi: 10.1177/1077546312458821 Lin M-L and Chen C-W (2014) Fuzzy neural modeling for n-degree ecosystems using the linear matrix inequality approach Journal of Vibration and Control 20 (1): 82-93. Epub ahead of print 8 October 2012. doi: 10.1177/1077546312458533 Chen C-H, Wu W-X and Chen C-Y (2013) Ant-inspired collective problem-solving systems Journal of Vibration and Control 19 (16): 2481-2490. Epub ahead of print 18 September 2012. doi: 10.1177/1077546312456231 Chen C-H, Yao T-K, Kuo C-M and Chen C-Y (2013) Evolutionary design of constructive multilayer feedforward neural network Journal of Vibration and Control 19 (16): 2413-2420. Epub ahead of print 12 September 2012. doi: 10.1177/1077546312456726 Chen C-W (2013) Applications of the fuzzy-neural Lyapunov criterion to multiple time-delay systems Journal of Vibration and Control 19 (13): 2054-2067. Epub ahead of print 16 August 2012. doi: 10.1177/1077546312451034 Chung P-Y, Chen Y-H, Walter L and Chen C-Y (2013) Influence and dynamics of a mobile robot control on mechanical components Journal of Vibration and Control 19 (13): 1923-1935. Epub ahead of print 20 July 2012. doi: 10.1177/1077546312452184 Chen C-W (2013) Neural network-based fuzzy logic parallel distributed compensation controller for structural system Journal of Vibration and Control 19 (11): 1709-1727. Epub ahead of print 22 June 2012. doi: 10.1177/1077546312442233 Chen C-W, Yeh K, Yang H-C, Liu KFR and Liu C-C (2013) A critical review of structural system control by the large-scaled neural network linear-deferential-inclusion-based criterion Journal of Vibration and Control 19 (11): 1658-1673. Epub ahead of print 18 June 2012. doi: 10.1177/1077546312443377 Chen C-H, Kuo C-M, Chen C-Y and Dai J-H (2013) The design and synthesis using hierarchical robotic discrete-event modeling Journal of Vibration and Control 19 (11): 1603-1613. Epub ahead of print 27 June 2012. doi: 10.1177/1077546312449645 Chang CJ, Chen CY and Chou I-T (2013) The design of information and communication technologies: telecom MOD strength machines Journal of Vibration and Control 19 (10): 1499-1513. Epub ahead of print 27 June 2012. doi: 10.1177/1077546312449644 Shih B-Y, Chen C-Y, Li K-H, Wu T-Y, Chen G-Y (2013) A novel NXT control method for implementing force sensing and recycling in a training robot Journal of Vibration and Control 19 (10): 1443-1459. Epub ahead of print 1 June 2012. doi: 10.1177/1077546312446361 Chen C-W, Chen P-C and Chiang W-L (2013) Modified intelligent genetic algorithm-based adaptive neural network control for uncertain structural systems Journal of Vibration and Control 19 (9): 1333-1347. Epub ahead of print 31 May 2012. doi: 10.1177/1077546312442232 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Enhancing robust and stability control of a humanoid biped robot: system identification approach. Journal of Vibration and Control 19 (8): 1199-1207. Epub ahead of print 26 April 2012. doi: 10.1177/1077546312442947 Chang C-J, Chen C-Y and Huang C-W (2013) Applications for medical recovery using wireless control of a bluetooth ball with a hybrid G-sensor and human-computer interface technology Journal of Vibration and Control 19 (8): 1139-1151. Epub ahead of print 24 April 2012. doi: 10.1177/1077546312442948 Hsu W-K, Chiou D-J, Chen C-W, Liu M-Y, Chiang W-L and Huang P-C (2013) Sensitivity of initial damage detection for steel structures using the Hilbert-Huang transform method Journal of Vibration and Control 19 (6): 857-878. Epub ahead of print 29 February 2012. doi: 10.1177/1077546311434794 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Human–machine interface for the motion control of humanoid biped robots using a graphical user interface Motion Editor Journal of Vibration and Control 19 (6): 814-820. Epub ahead of print 23 February 2012. doi: 10.1177/1077546312437804 Chen C-Y (2013) Internal wave transport, nonlinear manifestation, and mixing in a stratified shear layer - technical briefs Journal of Vibration and Control 19 (3): 429-438. Epub ahead of print 18 January 2012. doi: 10.1177/1077546311429337 Chen C-W (2013) Delay independent criterion for multiple time-delay systems and its application in building structure control systems Journal of Vibration and Control 19 (3): 395-414. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429341 Chen C-Y, Shih B-Y, Shih C-H and Wang L-H (2013) Design, modeling and stability control for an actuated dynamic walking planar bipedal robot Journal of Vibration and Control 19 (3): 376-384. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429476 Liu K-C, Liu Y-W, Chen C-Y and Huang W-C (2013) Nonlinear vibration of structural deterioration in reinforced concrete columns: experimental and theoretical investigation Journal of Vibration and Control 19 (3): 323-335. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429477 Chen C-Y, Shih B-Y and Ma J-m (2013) Development for low-cost and cross-platform robot control environment Journal of Vibration and Control 19 (2): 228-233. Epub ahead of print 11 January 2012. doi: 10.1177/1077546311430107 Shih B-Y, Chang H and Chen C-Y (2013) Path planning for autonomous robots – a comprehensive analysis by a greedy algorithm Journal of Vibration and Control 19 (1): 130-142. Epub ahead of print 17 January 2012. doi: 10.1177/1077546311429841 Liu T-Y, Chiang W-L, Chen C-W, Hsu W-K, Lin C-W, Chiou D-J and Huang P-C (2012) Structural system identification for vibration bridges using the Hilbert–Huang transform Journal of Vibration and Control 18 (13): 1939-1956. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428347 Chen C-W (2012) Applications of the fuzzy Lyapunov linear matrix inequality criterion to a chaotic structural system Journal of Vibration and Control 18 (13): 1925-1938. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428346 Chen C-W (2012) Applications of linear differential inclusion-based criterion to a nonlinear chaotic system: a critical review Journal of Vibration and Control 18 (12): 1886-1899. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311428345 Shih B-Y, Chen C-Y and Chou W (2012) An enhanced obstacle avoidance and path correction mechanism for an autonomous intelligent robot with multiple sensors Journal of Vibration and Control 18 (12): 1855-1864. Epub ahead of print 14 December 2011. doi: 10.1177/1077546311426734 Chen C-W, Yeh K, Liu KFR and Lin M-L (2012) Applications of fuzzy control to nonlinear time-delay systems using the linear matrix inequality fuzzy Lyapunov method Journal of Vibration and Control 18 (10): 1561-1574. Epub ahead of print 18 October 2011. doi: 10.1177/1077546311410765 Chen C-Y (2012) A critical review of internal wave dynamics. Part 2 – Laboratory experiments and theoretical physics Journal of Vibration and Control 18 (7): 983-1008. Epub ahead of print 21 September 2011. doi: 10.1177/1077546310397561 Chen C-Y and Huang P-H (2012) Review of an autonomous humanoid robot and its mechanical control Journal of Vibration and Control 18 (7): 973-982. Epub ahead of print 21 September 2011. doi: 10.1177/1077546310395974 Shih B-Y, Chen C-Y, Chang H and Ma J-m (2012) Dynamics and control for robotic manipulators using a greedy algorithm approach Journal of Vibration and Control 18 (6): 859-866. Epub ahead of print 25 August 2011. doi: 10.1177/1077546311407649 Yeh K, Chen C-W, Lo DC and Liu KFR (2012) Neural-network fuzzy control for chaotic tuned mass damper systems with time delays Journal of Vibration and Control 18 (6): 785-795. Epub ahead of print 15 August 2011. doi: 10.1177/1077546311407538 Chen C-Y, Shih B-Y, Shih C-H and Chou W-C (2012) The development of autonomous low-cost biped mobile surveillance robot by intelligent bricks Journal of Vibration and Control 18 (5): 577-586. Epub ahead of print 21 April 2011. doi: 10.1177/1077546310371349 Chen C-Y (2012) A critical review of internal wave dynamics. Part 1 – Remote sensing and in-situ observations Journal of Vibration and Control 18 (3): 417-436. Epub ahead of print 13 July 2011. doi: 10.1177/1077546310395971 Tseng C-P, Chen C-W and Liu KFR (2012) Risk control allocation model for pressure vessels and piping project Journal of Vibration and Control 18 (3): 385-394. Epub ahead of print 13 July 2011. doi: 10.1177/1077546311403182 Lin M-L and Chen C-W (2011) Stability analysis of community and ecosystem hierarchies using the Lyapunov method Journal of Vibration and Control 17 (13): 1930-1937. Epub ahead of print 9 December 2010. doi: 10.1177/1077546310385737 Chen C-Y, Shih B-Y, Chou W-C, Li Y-J and Chen Y-H (2011) Obstacle avoidance design for a humanoid intelligent robot with ultrasonic sensors Journal of Vibration and Control 17 (12): 1798-1804. Epub ahead of print 26 November 2010. doi: 10.1177/1077546310381101 Chen C-W (2011) Fuzzy control of interconnected structural systems using the fuzzy Lyapunov method Journal of Vibration and Control 17 (11): 1693-1702. Epub ahead of print 23 November 2010. doi: 10.1177/1077546310379625 Shih B-Y, Chen C-Y and Chou W-C (2011) Obstacle avoidance using a path correction method for autonomous control of a biped intelligent robot Journal of Vibration and Control 17 (10): 1567-1573. Epub ahead of print 22 November 2010. doi: 10.1177/1077546310372004 Tang J-P, Chiou D-J, Chen C-W, Chiang W-L, Hsu W-K, Chen C-Y and Liu T-Y (2011) A case study of damage detection in benchmark buildings using a Hilbert-Huang Transform-based method Journal of Vibration and Control 17 (4): 623-636. Epub ahead of print 8 November 2010. doi: 10.1177/1077546309360053 Liu TY, Chiang WL, Chen CW, Hsu WK, Lu LC and Chu TJ (2011) Identification and monitoring of bridge health from ambient vibration data Journal of Vibration and Control 17 (4): 589-603. Epub ahead of print 12 November 2010. doi: 10.1177/1077546309360049 Lin JW, Huang CW, Shih CH and Chen CY (2011) Fuzzy Lyapunov Stability Analysis and NN Modeling for Tension Leg Platform Systems Journal of Vibration and Control 17 (1): 151-158. Epub ahead of print 25 August 2010. doi: 10.1177/1077546309350477 Lee WI, Chen CY, Kuo HM and Sui YC (2010) The Development of Half-circle Fuzzy Numbers and Application in Fuzzy Control Journal of Vibration and Control 16 (13): 1977-1987. Epub ahead of print 22 April 2010. doi: 10.1177/1077546309349849

An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperature. A three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal-ash particles impacting some widely used superalloys and coatings at different angles. The presented results show the variation of the particle restitution ratios with the impingement angle for the coated and uncoated superalloys. The erosion behaviors of INCO-738, MAR 246 and X40 superalloys and protective coatings C, N, RT22 and RT22B also have been investigated experimentally at high temperature using a specially designed erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate (weight loss per unit weight of particles). Based on the experimental results of the particle mass effect on both weight losses and erosion rates, the coating lives have been estimated for different particle concentrations.

A study measuring the effects of a molten sulfate/chloride salt on the creep/fatigue behavior of a nickel base turbine blade superalloy, Udimet 720, at 1300°F (704°C) is described. Cyclic stress–cycles to failure (S-N) curves were generated at high mean stress levels, with mean stress, maximum stress, or the ratio of minimum to maximum stress (R ratio) held constant. In salt, it was found that when maximum stress is above the yield, with the cyclic component 20 percent of the maximum, failure occurs by stress corrosion fatigue in orders of magnitude less time than for corresponding loading conditions in air. It is significant, from a failure analysis point of view, that fatigue fracture is intergranular in these circumstances. Similar fatigue behavior may be expected for other nickel base alloys, however, at substantially lower maximum stresses in as much as Udimet 720 exhibits superior short time rupture strength, i.e., resistance to this form of stress corrosion, over the other blade alloys evaluated in this environment.

Abstract The use of recycled polymers in natural fiber-based composites provides an additional competitive advantage with their environmentally friendly properties. This study utilizes recycled high-density polyethylene (r-HDPE) as a composite matrix with bamboo fiber reinforcement that has been treated with an alkaline process. This study aims to analyze the mechanical properties and thermal properties of r-HDPE composites manufactured by extrusion molding with different bamboo fiber loadings. The specimens were subjected to tensile and impact testing for evaluating the mechanical properties. Thermogravimetric analysis (TGA) was performed to identify thermal stability, while the differential scanning calorimeter (DSC) was used to analyze the melting point phase of each specimen. This study indicated that the tensile strength of the composites decreases with increase of fiber fraction. The composite with 0% bamboo fiber showed the highest tensile strength of 8.3 N/mm2, while the lowest tensile strength is shown by the composite with 30% of bamboo fiber. Scanning electron microscopy showed porosity, pull-out, fiber cracking as the indicators for the material failure during tensile testing. From the impact test, it can be shown that the composite with 10% bamboo fiber records the highest impact strength at 37.7 J/m2. The TGA indicated high thermal stability of r-HDPE composites with 10% of bamboo fiber at 362.4°C temperature. A similar result was also exhibited from the DSC test, where the material with 10% fiber loading shows a big change in melting phase temperature. This research evidences the effect of bamboo fiber in increasing the impact strength and thermal stability of recycled HDPE matrix. This material could be the alternative for light-bearing applications such as automotive indoor components.

Lithium-ion batteries (LIBs) have found widespread application in energy storage due to their high energy density, low self-discharge and low maintenance characteristics. However, the stability and longevity of the batteries under extreme operating conditions is yet to be fully understood. Numerous experimental and simulation studies have been performed to elucidate the effect of temperature, current, depth of discharge, and the number of cycles [1,2,3] on the performance of LIBs. These studies show that the solid-electrolyte interface (SEI) layer and gas formation accelerate at high C-rates due to increased electrolyte decomposition [4,5]. Consequently, the cell's internal resistance increases, resulting in ever-increasing irreversible heat generation inside the cell [6]. This heat generation leads to high internal temperature and a corresponding reduction in cell capacity. The data of cell temperature for a wide range of ambient temperatures and cycling rates is limited because cell performance is typically reported at room temperature. The design of battery packs for electric vehicles(EVs) is also based on test data taken at room conditions. Given that the cell's capacity, specific energy, maximum power output is bound to depend on C-rate and ambient temperature, it is necessary to test and design battery packs based on these parameters. The thermal characteristics of a lithium-ion cell can be predicted using a physics-based thermal model or data-driven methods (DDM) relying on empirical data. Experimental determination of internal cell parameters required in physics-based thermal models is challenging and time-consuming for commercial cells. On the other hand, DDM requires only cell cycling data at specific operating conditions, thereby eliminating the need for internal parameter estimation. This model predicts the experimental input and output data pattern and fits the response surface to estimate the unknown output. In this study, surrogate modelling has been employed to estimate the surface temperature, capacity, energy, and average power of commercial lithium-ion cells for different discharge currents and ambient temperatures. Surrogate modelling, a popular data analysis and reduced-order modelling technique, aims to find a global minimum of a particular objective function using a few objective function evaluations [7]. The surrogate-based model divides experimental data into training and test data sets. The training data set is employed to train the algorithm. After that, the testing data set is used to validate the model's accuracy. Experiments were performed to develop a surrogate model, with the number of experiments decided using the design of experiments[8] for a current range of 0.5C to 3C-rate and ambient temperature range of 0°C to 45°C . The cycling of cells was performed using a high current battery cycler (Arbin), and the ambient temperature was maintained using a thermal chamber (Cincinnati). The surface temperature of commercial 18650 (NMC811) lithium-ion cells was recorded using T-type thermocouples and a National Instruments DAQ module. A polynomial response surface was fitted using surrogate modelling on experimentally obtained data. The response surface shown in figure 1. contains nine data points for the preliminary study, sub-divided into a set of seven training and two testing data. The prediction error sum of squares (PRESS) is currently bounded within 10% due to the limited training data set availability and is expected to be within a band of 1% after adding data from ongoing experiments. The estimation of temperature, capacity, and specific energy can be used to optimize and develop an improved thermal management system for electric vehicles that works under various operating conditions. References Waldmann, T., Wilka, M., Kasper, M., Fleischhammer, M., & Wohlfahrt-Mehrens, M. (2014). Journal of Power Sources, 262, 129-135. Guan, T., Sun, S., Yu, F., Gao, Y., Fan, P., Zuo, P., Du,C., & Yin, G. (2018). Electrochimica Acta, 279, 204-212. Simolka, M., Heger, J. F., Traub, N., Kaess, H., & Friedrich, K. A. (2020). Journal of The Electrochemical Society, 167(11), 110502. Xu, B., Diao, W., Wen, G., Choe, S. Y., Kim, J., & Pecht, M. (2021). Journal of Power Sources, 510, 230390. Rashid, M., & Gupta, A. (2017). Electrochimica Acta, 231, 171-184. Leng, F., Tan, C. M., & Pecht, M. (2015). Scientific reports, 5(1), 1-12. Queipo, N. V., Haftka, R. T., Shyy, W., Goel, T., Vaidyanathan, R., & Tucker, P. K. (2005). Progress in aerospace sciences, 41(1), 1-28. Li, W., Xiao, M., Peng, X., Garg, A., & Gao, L. (2019). Applied Thermal Engineering, 147, 90-100. Figure 1

Primary batteries have been used in past deep space exploration missions, providing power for periods of several hours to several days of mission operations [1,2]. Future missions planned by the National Aeronautics and Space Administration (NASA) will require more advanced primary batteries to provide power to missions for up to 60 days [3]. The Li/CFx primary battery chemistry has a high specific energy, low self-discharge rate, and a relatively wide operating temperature range which makes it a suitable power source for extended mission durations in deep space, particularly for applications involving low to moderate discharge rates [4]. Li/CFx batteries have not been used in any NASA missions to date, and are now being developed for the Europa Lander mission concept [5]. An extensive evaluation of EaglePicher’s D-sized Li/CFx cells is underway, to benchmark the calendar life performance, radiation tolerance, and performance under different temperatures and currents. One of the unique characteristics of the Li/CFx chemistry is the extremely flat voltage plateau during cell discharge (Figure 1) [6, 7]. As the cell approaches end of life, its voltage quickly drops prior to reaching the 1.5V recommended discharge limit. While the cell’s stable voltage is a key component to the high specific energy of this chemistry, it also makes it challenging to accurately predict the battery’s remaining capacity. Premature battery depletion is a risk to mission success, and improved methods for determining depth-of-discharge (DOD) in this unique cell chemistry are of great interest. A pulse-discharge test method is developed and implemented to investigate the change in cell direct current internal resistance (DCIR) during discharge. Varied responses based on the discharge rate are observed and will be discussed. The resulting data are analyzed for possible correlation with DOD, along with changes in the cell voltage over various segments of the discharge curve. This talk discusses the test method and results achieved using the pulse-discharge test method. References: M. Hofland, E.J. Stofel, R.K. Taenaka, Aerospace and Electronic Systems Magazine IEEE, 11, 14 (1996). P. Dagarin, R.K. Taenaka, E.J. Stofel, Proc. of 31st Energy Conversion Engineering Conference 1996, 1, 427 (1996). P. Hand et al.2022 Planet. Sci. J. 3 22. Frederick C. Krause et al.2018 Electrochem. Soc. 165 A2312. Crum, R. et al 2021 Advanced Technology Developments for Europa Lander and other In-Situ Ocean World Missions. Bulletin of the AAS,53(4). Watanabe, N., & Fukuda, M. (1970). S. Patent No. 3,536,532. Washington, DC: U.S. Patent and Trademark Office. Watanabe, N., Endo, M., Ueno, K., Solid State Ionics, Vol. 1, Issue 5-6 (1980). The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the Europa Lander Pre-Project. Figure 1

Introduction: The frequent cause of liver disease in the whole world is due to Hepatitis C virus. According to the estimate the worldwide infection due to hepatitis C virus ranges from 150 to 200 million cases. Amongst these cases the chronic infection are found in about 85% cases. In the globe the most important cause of mortality and morbidity is Hepatitis C virus. In the whole world Chronic Liver disease and hepatocellular carcinoma of about 25% is due to hepatitis C virus. Objective: To find out the occurrence of metabolic syndrome in patients with chronic hepatitis C virus infection. Materials and Methods: This study was Descriptive cross sectional research study, which was directed at Department of Medicine, Hayat Abad Medical complex, Peshawar, Khyber Pakhtunkhwa Pakistan. The time duration for our study was 8 month. In our study about 147 patient were observed to find out the frequency of metabolic syndrome in patients with chronic hepatitis C virus infection Results: According to the results of our study, among 147 patients the analysis of age wise distribution was as follow; n= 20-25 Years 6(4.1%), 26-30 Years 26(17.7%), 31-35 Years 51(34.7%), 36-40 Years 28(19.0%), 41-50 Years 22(15.0%) and in 51-60 Years it was 14(9.5%). 49.12 years having standard deviation of ±2.142 was the mean age in our study. In our study gender wise distribution, amongst 147 patients 108(73.5%) were male while 39(26.5%) were female. 131(89.1%) patients were observed to have metabolic syndrome with chronic hepatitis C virus infection. Conclusion: Our study concludes that there is no uncommon occurrence of metabolic syndrome in cases with HCV infection. There is significant association of metabolic syndrome with Hepatitis C Virus (HCV) when HCV infection have more than 3 year’s duration. Keywords: Frequency; Metabolic Syndrome; Chronic hepatitis C virus infection; Mortality; Morbidity

Iron redox flow batteries are a promising option for utility scale energy storage. In redox flow batteries (RFB), the power and energy storage capacities are decoupled, making them highly scalable 1,2. Due to its high abundance, low cost, and low toxicity, iron is very attractive as a reactive species for both the positive and negative half cells in large scale redox flow batteries 3. The Fe(II)/Fe(III) reaction is utilized at the positive electrode while the Fe(0)/Fe(II) reaction is used at the negative electrode. Unfortunately, the Fe(II) reduction reaction used in the negative cell involves plating solid iron onto the electrode during charge. This plating reaction limits the battery’s capacity based on the spatial constraints of the flow cell, coupling the power and storage capacities of the flow battery and limiting its scalability 2. Slurry electrodes, consisting of a dispersion of conductive particles in the electrode, have been proposed as solution for this issue4. By having the metal deposit onto the mobile dispersion of particles, as in Figure 1B, instead of the stationary electrode as in Figure 1A, the power and storage capacities of a hybrid flow battery can be decoupled. Slurry electrodes have also been proposed in a number of other applications such as water deionization and supercapacitors5. Their use has also been studied for use in fully soluble RFB chemistries, such as all-vanadium6,7. However, nearly all of the previous work in slurry electrodes has been in highly concentrated slurries in order to take advantage of the conductivity of the percolated particle network. Unfortunately, these highly loaded slurries can be viscous and can cause clogs and failures in a flowing system such as an RFB4,7. In this work, the electrochemical behavior of slurries below the percolation threshold are investigated via voltammetry in a custom flow cell. The percolation threshold of a slurry is identified and the modified behavior of the Fe (II)/Fe (III) reaction is measured as a function of slurry concentration and flow rate. The results suggest that significant enhancement of the electrochemically active surface area can be achieved below the percolation threshold. (1) Dinesh, A.; Olivera, S.; Venkatesh, K.; Santosh, M. S.; Priya, M. G.; Inamuddin; Asiri, A. M.; Muralidhara, H. B. Iron-Based Flow Batteries to Store Renewable Energies. Environ. Chem. Lett. 2018, 16 (3), 683–694. https://doi.org/10.1007/s10311-018-0709-8. (2) Weber, A. Z.; Mench, M. M.; Meyers, J. P.; Ross, P. N.; Jeffrey, T.; Liu, Q. Redox Flow Batteries , a Review Environmental Energy Technologies Division , Lawrence Berkeley National Laboratory , Department of Mechanical , Aerospace and Biomedical Engineering , University of Tennessee , Department of Chemical Engineering , McGill Un. 1–72. (3) Petek, T. J. Enhancing the Capacity of All-Iron Flow Batteries: Understanding Crossover and Slurry Electrodes. Ph.D. Thesis 2015, No. May. (4) Petek, T. J.; Hoyt, N. C.; Savinell, R. F.; Wainright, J. S. Slurry Electrodes for Iron Plating in an All-Iron Flow Battery. J. Power Sources 2015, 294, 620–626. https://doi.org/10.1016/j.jpowsour.2015.06.050. (5) Mourshed, M.; Niya, S. M. R.; Ojha, R.; Rosengarten, G.; Andrews, J.; Shabani, B. Carbon-Based Slurry Electrodes for Energy Storage and Power Supply Systems. Energy Storage Mater. 2021, 40 (April), 461–489. https://doi.org/10.1016/j.ensm.2021.05.032. (6) Percin, K.; van der Zee, B.; Wessling, M. On the Resistances of a Slurry Electrode Vanadium Redox Flow Battery. ChemElectroChem 2020, 7 (9), 2165–2172. https://doi.org/10.1002/celc.202000242. (7) Lohaus, J.; Rall, D.; Kruse, M.; Steinberger, V.; Wessling, M. On Charge Percolation in Slurry Electrodes Used in Vanadium Redox Flow Batteries. Electrochem. commun. 2019, 101 (March), 104–108. https://doi.org/10.1016/j.elecom.2019.02.013. Figure 1

Abstract This paper covers technological results achieved with silicon capacitors for Aerospace applications, including stability, reliability and frequency data at high temperatures, as well as thermal stress, vibration & shock tests and radiations stress, according to ESA TRP reference (n° T723-325QT).

Ti–B–C–N and Ti–Si–B–C–N nanocomposite coatings were deposited on AISI 304 stainless steel substrates by DC unbalanced magnetron sputtering from two (80mol% TiB2–20mol% TiC and 40mol% TiB2–60mol% TiC) composite targets in various Si target powers. The relationship among microstructures, mechanical properties, and tribologiacal properties was investigated. The synthesized Ti–B–C–N and Ti–Si–B–C–N coatings were characterized using x–ray diffraction (XRD) and x–ray photoelectron spectroscopy (XPS). These analyses revealed that the Ti–Si–B–C–N coatings are nanocomposites consisting of solid-solution (Ti,C,N)B2 and Ti(C,N) crystallites distributed in an amorphous TiSi2, SiC, and SiB4 matrix including some carbon, BN, CNx, TiO2, and B2O3 components. The addition of Si to the Ti–B–C–N coating led to percolation of amorphous TiSi2, SiC, and SiB4 phases. The Ti–Si–B–C–N coatings exhibited high hardness and H/E values, indicating high fracture toughness, of approximately 35 GPa and 0.098, respectively. Furthermore, the Ti–Si–B–C–N coatings exhibited very low wear rates ranging from ~3×10-7 to ~16×10-7 mm3/(N·m). The minimum friction coefficient of the Ti–Si–B–C–N coatings was approximately 0.15 at low Si target power between 25W and 50W. A systematic investigation on the microstructures, mechanical properties, and tribological properties of Ti–Si–B–C–N coatings prepared from two TiB2–TiC composite targets and one Si target is reported in this paper.

Abstract In this paper an associative-parametric approach is proposed in order to model the mesh of an aeronautical concept starting from a set of high-level structural primitives. This approach allows the designer to carry out the geometric modelling and the automatic mesh generation within one software environment in a fast and interactive way. The structural optimisation process is then simplified, with a relevant man-hours saving. A lower number of data transfers between different software is, moreover, involved with less problems related to the data corruption. To assure orders of continuity higher than C 0 between adjacent instances, a suitable mathematical description of the structural primitives has been proposed. This description assures the maintenance of the required continuity constraints when the mesh is modified. Appropriate schemes of dependences are identified to guarantee the automatic propagation of the modifications complying with the continuity constraints.

In order to study the mechanical properties and failure mechanism of the axial braided C/C composites, the microscopic and macroscopic mechanical properties of the composite were investigated. In view of the size effect of the samples, the properties of the samples with different thickness were tested. The strain during loading was measured by optical method, and the failure morphology was observed by SEM. The changing characteristics of stress-strain curve were analyzed, and the failure characteristics of materials and failure mechanism under various loads were obtained. It was found that brittle fracture was observed during the tensile process of axial braided C/C composites, and the main failure forms were fiber rod pulling and partial fiber rod breaking in the axial direction. Radial failure was mainly in the form of fiber bundle fracture and crack stratification propagation. When compressed, the material exhibited pseudoplastic characteristics. The radial compression sample was cut along a 45-degree bevel. The axial compression curve was in the form of double fold, the axial fiber rod was unstable, and the transverse fiber bundle was cut. During in-plane shearing, the axial fracture was brittle and the fiber rod was cut. The radial direction showed the fracture and pulling of the fiber bundle, and the material had the characteristics of pseudoplasticity. The research methods and results in this paper could provide important references for the optimization and rational application of C/C composite materials.