Добірка наукової літератури з теми "Micro-structure investigation"

The paper reports the investigation results of combined strengthening impact upon material micro-structure changes. On the basis of the investigations carried out there is described an impact of wave deformation strengthening process upon material micro-structure by the example of chromium-nickel alloyed steels. It is shown that ChTT+SPD strengthening ensures the increase of material stress-strain properties.

Managing capital structure is an imperative decision made by all firms. The manner in which financing is organized is a strategic financial decision and managers must settle on the amount of debt in relation to equity that it requires to maintain. Despite many empirical studies investigating the choice of capital structure for large corporates, minimal research has been conducted on capital structure decisions in small, medium, and micro enterprises (SMMEs). This study identifies major factors influencing the capital structure of SMMEs in a developing economy and enlightens owners/managers on the importance thereof. This investigation used a quantitative research approach, which was cross-sectional. A convenience sampling method was adopted, and data were collected from 136 respondents, only confined to the retail and whole sector, which is the second largest sector in KwaZulu-Natal, South Africa. The partial least squares structural equation modelling was utilized to determine the statistical results. It was discovered that managerial factors such as individual goals and financing preference of the owner/manager, network ties, attitude to debt, maintaining control and asymmetric information; and firm-level factors such as size of the firm, profitability and firm age are major factors that influence the capital structure of SMMEs. Therefore, capital structure decisions are made motivated by the attitudes of the owners/managers.

Model test investigation on rectangular section composite micro-pile structure used for earth slope reinforcement has been performed, including the mechanical and deformation properties and pile spacing influence on anti-sliding capacity. Test results have shown the main following conclusions. For the rectangular section composite micro-pile structure and the similar soil in tests, micro-pile row spacing along the lateral load direction ranging from 4D to 6D (D is the diameter of micro-pile) can provide higher anti-sliding capacity. Active earth pressure of the first row pile is larger than that of other piles when the anti-sliding potential of composite micro-pile structure is fully developed. Relative deformation of the first row pile is larger than that of the middle and last row piles above the slip surface, while relative deformation of the last row pile is larger than that of other piles beneath the slip surface. The main failure mode of the rectangular section composite micro-pile structure can be regarded as bending failure in certain range near the slip surface.

The original micro structure of the base metal is significantly affected by a welding thermal cycle, irrespective of the type of the heat source. Hence, new phases and different grain size result in the welding bead. The tensile strength of the overall structure is affected in turn. Tensile tests are normally conducted to eventually test a square butt joint configuration. In conjunction, micro hardness is thought to be a good indicator to predict where the fracture would occur in the welded structure. Referring to common metal alloys for aerospace and considering a diode-pumped disk-laser source, the response of the base metal to the laser beam is investigated in this paper. Autogenous welding of aluminum alloy 2024, autogenous welding of titanium alloy Ti-6Al-4V and dissimilar welding of Haynes 188 with Inconel 718 are discussed, with respect to micro structure changes in the fused zone and in the heat affected zone. The failure mode is examined.

Regular micro-surface structure in the form of micro-pores produced on the face of mechanical seals by laser technology can be used to improve the friction performance of the seal mating rings. A test rig with variable axial load was used to test laser-textured seal rings with micro-pores of various pore depth and pore ratio to study the effect of the laser-textured seal face structure parameters on the friction performance of mechanical seals. It is found that there are optimum texturing face parameters at which the friction torque and the face temperature rise of seal rings are minimum. Results of these tests show that the micro-pores on one of the seal mating faces can generate substantial hydrodynamic effect. Heat generation due to frictional contact on seal-ring surfaces is a major factor that causes deterioration of face seals and shortens their service life[1,2]. Excessive temperature rise can be avoided by improving structure of a seal surface. By means of laser technology return-flow structure, oblique line groove and spherical micro-pores are engraved on the seal face[3-5]. The research shows that substantial hydrodynamic effect can be generated between the seal faces with micro-pores[6-8]. In this study experiments are performed on laser-textured micro-pores seal faces at various axial loads to investigate the effect of the face structure and operating parameters on friction torque and face temperature rise.

Abstract: The characteristic of internal structure of filament wound composite is investigated by experiment in this article. Cylinders manufactured by two kinds of fiber, E-glass and carbon, and epoxy resin, are cut into several pieces along the winding direction. The sections of pieces are observed with optic microscope. The result shows that there are two kinds of structure in filament wound composite, laminate area and undulating area, consisting of interwoven fiber band in different directions. Undulating quantity is measured at a series of points along undulating fiber band; a linear model is adopted to model geometrical shape of undulation.

There are many variables that affect the viscoelastic properties of asphalt mixtures with time, among which age hardening may be considered one of the important ones. Age hardening of asphalt mixtures is an irreversible process, which contributes to a reduction of the durability of pavements and eventually increases the maintenance cost. Beside the environmental effects, ageing in asphalt mixture depends on the physicochemical properties of bitumen and mixture morphology which is a combined effect of aggregate packing, porosity, air void distribution and their interconnectivity. Thus, a clear understanding on the physicochemical properties of bitumen and mixture morphology may help to predict the performance of asphalt mixtures, which will contribute to longer-lasting and better performing pavements. When looking at the bitumen at micro-scale, one can see microstructures appearing under certain conditions which can be partially explained by the interaction of the individual phases. Since the thermo-rheological behavior of bitumen depends largely on its chemical structure and intermolecular microstructures, studying these can lead to understanding of the mechanism, speed and conditions under which this phase behavior occurs. Linking this to the changes in properties of bitumen can thus lead to better understanding of the causes of ageing, its dominant parameters and the resulting diminished mechanical response. To investigate ageing in asphalt pavements, along with physicochemical properties of bitumen one needs to also focus on the influence of mixture morphology.  It is known that asphalt mixtures with similar percentages of air-voids can have different morphologies and thus can age differently. Prediction of ageing behavior without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. Hence, it is important to understand the interplay between the mixture morphology and ageing susceptibility and relate this to the long term mixture performance. The aim of this Thesis was to develop fundamental understanding on ageing in asphalt mixtures that can contribute to the asphalt community moving away from the currently used accelerated ageing laboratory tests and empirical models that can lead to erroneous conclusions. To reach this aim, experimental and numerical micro-scale analyses on bitumen and meso-scale investigations on mixture morphology have been performed which, collectively, allowed for the development of a method for the prediction of asphalt field ageing, incorporating both mixture morphology and micro-scale bitumen mechanisms. For this, first, the mechanisms of surface ageing and diffusion controlled oxidative ageing were identified. Secondly, the influence of mixture morphology on asphalt ageing susceptibility was investigated. Procedures to determine the controlling parameter were then developed and an empirical framework to quantify the long-term field ageing of asphalt mixtures was set-up. For this, a combination of experimental and numerical methods was employed. An extensive experimental study was carried out to understand the fundamental mechanisms behind the micro-structural phase appearance and the speed or mobility at which they change. Atomic Force Microscopy (AFM) was utilized at different temperatures to investigate the phase separation behavior for four different types of bitumen and co-relate it with the Differential Scanning Calorimetry (DSC) measurements. Based on the experimental findings, it was concluded that the observed phase separation is mainly due to the wax/paraffin fraction presence in bitumen (Paper I). A hypothesis was developed of the appearance of a thin film at the specimen surface due to ageing which is creating a barrier, restricting thus the microstructures to float towards the surface. Furthermore, investigation showed that depending on the bitumen and exposure types this surface thin film is water soluble and thus the moisture damage becomes more severe with the ageing of asphalt pavement (Paper II and IV). A new empirical relation to obtain the primary structure coating thickness was established utilizing mixture volumetric properties and gradation using a large set of data from different literature sources. It was found that the enhanced morphological framework can be used to optimize the long term performance of asphalt mixtures (Paper III).  Thereafter, the effect of diffusion controlled oxidative ageing on different mixture morphologies based on oxidative ageing mechanism of bitumen and diffusion-reaction process was investigated using the Finite Element Method (FEM). From the FE analyses, the effect of air-void distribution and their interconnectivity combined with the aggregate packing was shown to have a significant effect on age hardening (Paper IV). It was shown that focusing only on the percentage of air-void as the main predictive ageing parameter may lead to an erroneous conclusion and non-optimal predictions of long-term behavior.  To replace such approaches, a new way to predict the long-term ageing was proposed in this Thesis, utilizing the found influences of mixture morphology and fundamental mechanism. Though additional mechanisms and non-linear coupling between them may be still needed to reach the ‘ultimate’ ageing prediction model, the current model was found to be a significant improvement to the currently used methods and may lead the way towards further enhancing the fundamental knowledge towards asphalt mixture ageing (Paper V).

QC 20140509

Osteoporosis is a disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. Osteoporosis affects over 200 million people worldwide, with an estimated 1.5 million fractures annually in the United States alone, and with attendant costs exceeding $10 billion dollars per annum. Osteoporosis reduces bone density through a series of structural changes to the honeycomb-like trabecular bone structure (micro-structure). The reduced bone density, coupled with the microstructural changes, results in significant loss of bone strength and increased fracture risk. Vertebral compression fractures are the most common type of osteoporotic fracture and are associated with pain, increased thoracic curvature, reduced mobility, and difficulty with self care. Surgical interventions, such as kyphoplasty or vertebroplasty, are used to treat osteoporotic vertebral fractures by restoring vertebral stability and alleviating pain. These minimally invasive procedures involve injecting bone cement into the fractured vertebrae. The techniques are still relatively new and while initial results are promising, with the procedures relieving pain in 70-95% of cases, medium-term investigations are now indicating an increased risk of adjacent level fracture following the procedure. With the aging population, understanding and treatment of osteoporosis is an increasingly important public health issue in developed Western countries. The aim of this study was to investigate the biomechanics of spinal osteoporosis and osteoporotic vertebral compression fractures by developing multi-scale computational, Finite Element (FE) models of both healthy and osteoporotic vertebral bodies. The multi-scale approach included the overall vertebral body anatomy, as well as a detailed representation of the internal trabecular microstructure. This novel, multi-scale approach overcame limitations of previous investigations by allowing simultaneous investigation of the mechanics of the trabecular micro-structure as well as overall vertebral body mechanics. The models were used to simulate the progression of osteoporosis, the effect of different loading conditions on vertebral strength and stiffness, and the effects of vertebroplasty on vertebral and trabecular mechanics. The model development process began with the development of an individual trabecular strut model using 3D beam elements, which was used as the building block for lattice-type, structural trabecular bone models, which were in turn incorporated into the vertebral body models. At each stage of model development, model predictions were compared to analytical solutions and in-vitro data from existing literature. The incremental process provided confidence in the predictions of each model before incorporation into the overall vertebral body model. The trabecular bone model, vertebral body model and vertebroplasty models were validated against in-vitro data from a series of compression tests performed using human cadaveric vertebral bodies. Firstly, trabecular bone samples were acquired and morphological parameters for each sample were measured using high resolution micro-computed tomography (CT). Apparent mechanical properties for each sample were then determined using uni-axial compression tests. Bone tissue properties were inversely determined using voxel-based FE models based on the micro-CT data. Specimen specific trabecular bone models were developed and the predicted apparent stiffness and strength were compared to the experimentally measured apparent stiffness and strength of the corresponding specimen. Following the trabecular specimen tests, a series of 12 whole cadaveric vertebrae were then divided into treated and non-treated groups and vertebroplasty performed on the specimens of the treated group. The vertebrae in both groups underwent clinical-CT scanning and destructive uniaxial compression testing. Specimen specific FE vertebral body models were developed and the predicted mechanical response compared to the experimentally measured responses. The validation process demonstrated that the multi-scale FE models comprising a lattice network of beam elements were able to accurately capture the failure mechanics of trabecular bone; and a trabecular core represented with beam elements enclosed in a layer of shell elements to represent the cortical shell was able to adequately represent the failure mechanics of intact vertebral bodies with varying degrees of osteoporosis. Following model development and validation, the models were used to investigate the effects of progressive osteoporosis on vertebral body mechanics and trabecular bone mechanics. These simulations showed that overall failure of the osteoporotic vertebral body is initiated by failure of the trabecular core, and the failure mechanism of the trabeculae varies with the progression of osteoporosis; from tissue yield in healthy trabecular bone, to failure due to instability (buckling) in osteoporotic bone with its thinner trabecular struts. The mechanical response of the vertebral body under load is highly dependent on the ability of the endplates to deform to transmit the load to the underlying trabecular bone. The ability of the endplate to evenly transfer the load through the core diminishes with osteoporosis. Investigation into the effect of different loading conditions on the vertebral body found that, because the trabecular bone structural changes which occur in osteoporosis result in a structure that is highly aligned with the loading direction, the vertebral body is consequently less able to withstand non-uniform loading states such as occurs in forward flexion. Changes in vertebral body loading due to disc degeneration were simulated, but proved to have little effect on osteoporotic vertebra mechanics. Conversely, differences in vertebral body loading between simulated invivo (uniform endplate pressure) and in-vitro conditions (where the vertebral endplates are rigidly cemented) had a dramatic effect on the predicted vertebral mechanics. This investigation suggested that in-vitro loading using bone cement potting of both endplates has major limitations in its ability to represent vertebral body mechanics in-vivo. And lastly, FE investigation into the biomechanical effect of vertebroplasty was performed. The results of this investigation demonstrated that the effect of vertebroplasty on overall vertebra mechanics is strongly governed by the cement distribution achieved within the trabecular core. In agreement with a recent study, the models predicted that vertebroplasty cement distributions which do not form one continuous mass which contacts both endplates have little effect on vertebral body stiffness or strength. In summary, this work presents the development of a novel, multi-scale Finite Element model of the osteoporotic vertebral body, which provides a powerful new tool for investigating the mechanics of osteoporotic vertebral compression fractures at the trabecular bone micro-structural level, and at the vertebral body level.

Do telecommunications (telecoms) technologies contribute to the economic growth of organisations and the individuals that make up these organisations? This is the question this research sets out to answer. The study was motivated by the numerous macro-level and predominantly economic studies that suggest the existence of a causal relationship between the telecommunication infrastructure available within a country and its level of economic growth and/or development. If telecoms indeed have this causal effect why is this not being reported by studies on the everyday business lives of ordinary citizens? This research adds to the body of literature that investigates the impact of telecoms at the micro-level. It examines the way in which telephones are used by participants in a developing country micro-industry. Furthermore, this examination is conducted in 'context - it studies the application of telephones in fulfilling a specific need; the need to obtain and distribute information. The research therefore begins with an assessment of the impact, lack or uneven distribution of information, has on the behaviour of organisations and individuals in a specified case industry. The research documents these impacts and investigates what the industry's response has been in overcoming the limitations they have on trade. It is in investigating the response of the industry that the contribution of telephones is examined - does the use of the telephone add noticeably to the improvement of trade in the industry? The research found that, as stated in literature, telephones do improve the ability of industry participants to acquire and distribute information. In some instances this improved ability has generated benefits. For example, telephones have improved the efficiency with which participants choose who to trade with. Telephones also contribute to cost savings in the industry by helping participants to economise on communication and transportation costs. Distance between production and consumption is also better managed through telecom use, and is in some cases more efficient than physical movement between places. However, the use of telephones in certain circumstances is not always effective. For example, selecting the most appropriate trade partner requires access to private information about the alternatives. However, private information (i. e. information only known to one party to a trade) is mainly acquired through personal observation. When it is transmitted through a third-party it is within the context of an already established relationship based on trust or mechanism for sanctions. In an industry with low levels of trust between participants - as in the case study; acquisition, verification and distribution of private information is critical to success. Under such circumstances the mere use of telephone adds little value. However, when telephone use occurs within the context of established organisational forms in the industry, its benefits are reinforced.

碩士
淡江大學
機械工程學系
86
Duo to the mature of semiconductor process technology, the study on the MEMS "Micro Electro Mechanical System" is will developing. Micro joining structures can be applied to bio-engineering, aerospace - engineering and medical engineering. 　　In the paper, we use semiconductor process to sfabricate many micro elastic deflection of Sio2 and SINx flanges angles on (100) silicon wafer that acts as mechanical adhesives structure between two wafer surfaces. 　　The micro structures fastening system do not need any chemical adhesive, heat or ultrasonic vibrations, it is a pure mechanical interlocking devic e. The structure is 18□m x 18□m by 12□m high , there are approximately 200,000 individual structure per cm2 of substrate, resulting in a strong strength of the join to be in excess of 400kpa. 　　We have make some database for the fabrication process of the micro structures. The result can apply t the areas where need micro joining structureds including medical uses (joinging tissues) and IC packaging.

博士
國立中央大學
物理研究所
99
The microscopic liquid can be treated as a strongly coupled many-body system, which exhibits vast and complicated micro-dynamics. It has been a hot topic in the past decade. Nevertheless, the previous studies are mainly limited to the system with isotropic coupling. It is very interesting to extend the investigation to the liquid with anisotropic coupling. 2+1D liquids composed of bundles of flexible chains is one of the simplest examples, where the coupling along the chain direction is stronger than that in the transverse plane. Due to the lack of direct experimental observation, the micro-picture of 2+1D liquid remains elusive. The dusty plasma liquid formed by negatively charged dust particle suspended in low pressure gaseous discharges, where the dust particle interacts with each other through the Coulomb interaction, provides us a platform to mimic and understand the generic microscopic dynamical behaviors of liquids at the kinetic level because of the capability of direct visualization. The wake field of downward ion wind on particles at larger diameter (> 3 mum) provides extra vertical coupling and alignment, and induces the chain bundle structure. When the chain length is long (40 particle per chain), the chains are flexible. The 2+1D dusty plasma liquid is then formed. In this work, the micro-structure and motion in the cold 2+1D dusty plasma liquid were experimentally investigated through our stereo scanning dust tracking system. It is found that the horizontal structure and motion are similar to those of the 2D liquids. When the observation time is shorter than the relaxation time of the system, particles can exhibit collective motion, which is also associated with anomalous diffusion. Horizontally, the collective motion can be classified to the longitudinal and the transverse types. Along the vertical chain, under the suppression of the vertical flipping, only the transverse type collective motion is allowed. The cooperation of horizontal and vertical collective motion leads to the special collective stereo excitations, such as straight vertical chains with small amplitude wiggling, chain tilting-restraightening, bundle twisting-restraightening, and chain breaking-reconnection. The demonstration of the first direct visualization of those basic excitations was conducted in this work. In addition, horizontal micro-structure and the stereo collective excitations are found to be statistically correlated through the measurement of correlation probability.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

The chapter outlines seven ideal-typical models for thinking about the politics of police. The models are not mutually exclusive and can be combined to form complex descriptions of theoretical relations. They rest on a variety of conceptual distinctions. Crime control and due process; high and low policing; police force and police service; organizational structure and officer discretion; state, market, and civil society; police knowledge work, investigation and intelligence; and the democratic, authoritarian, and totalitarian politics of policing are all discussed. The police métier is discussed a set of habits and assumptions that envisions only the need to control, deter, and punish. It has evolved around the practices of tracking, surveillance, keeping watch and unending vigilance, and the application of force, up to and including fatal force. The chapter concludes that these seven models for thinking about police and policing facilitate micro-, meso-, and macro-level analysis.

Direct stress and sub-stress caused by fire, temperature variation and external loading in a structure are most important for the development of cracks. The chemical reactions of natural healing in the matrix was not been established conclusively. The most significant factor that influences the self-healing is the precipitation of calcium carbonate crystals on the crack surface. The mechanism which contribute autogenic healing are: (a) Continued hydration of cement at cracked surface as well as continued hydration of already formed gel and also inter-crystallization of fractured crystals; (b) blocking of flow path by water impurities and concrete particles broken from the crack surface due to cracking; (c) expansion of concrete in the crack flank (swelling) and closing of cracks by spalling of loose concrete particle are also reported as the sealing mechanism by researchers. The recovery of mechanical as well as physical property was discussed by different researchers. An experimental investigation was carried out to study the autogenic healing of fire damaged fly ash and conventional cementitious mortar samples subjected to steam followed by water curing at normal atmospheric pressure. The micro cracks are generated artificially by heating the 28 days aged mortar samples at 800 Deg. C. The effect of fly-ash replacing ordinary Portland cement by 0 and 20% was studied. Recovery of compressive strength and physical properties i.e. apparent porosity, water absorption, ultrasonic pulse velocity and rapid chloride ion penetration test confirm the self-healing of micro cracks. Such healing is more prominent for fly ash mortar mix. Optical as well as scanning electron microscopy With EDAX analysis and X-ray diffraction study of the white crystalline material formed in the crack, confirms formation of calcium carbonate.

Throughout the Arabian Gulf and beyond, higher education students face the challenge of learning to write academic essays in English though possessing limited ability in the language. Scaffolding writing techniques provide support for them as they learn about essay structure while working within their Zone of Proximal Development (i.e. in the metaphorical space between what learners can accomplish unassisted and what they cannot do on their own). This chapter discusses the results of classroom research on how scaffolding writing instruction in English affected tertiary student writing outcomes in the Sultanate of Oman. Instructional techniques used in the study, which include aspects of the Hammond and Gibbons (2005) macro and micro ESL scaffolding model, as well as modeling and collaborative writing, are discussed in detail. The results of the study found that using scaffolding writing techniques revived students' forgotten knowledge of essay structure during approximately ten hours of instruction. In addition, data showed that students favored this instructional strategy.

Wire electrochemical micro machining (WEMM) using the online-fabricated micro wire electrode is proposed as a new method of micro machining. Based on electrochemical principle, the mechanism of nanosecond pulses WEMM was investigated. The hardware of the control system was founded using devices of virtual instruments, and the software of the system was designed based on Labwindows/CVI. The micrometer scale wire electrode was online fabricated, the diameter of wire electrode was real-time monitored by precisely measuring the variation in resistance of the electrode, and it is possible that accomplish the fabrication of wire electrode and the following processes continuously in the same machining system. The relations between the machining accuracy and parameters, such as velocity of feed forward and pulses parameters was experimentally studied, and a series of high-aspect-ration micro structure and multi-microgrooves were fabricated. The research of the paper sets up a firm foundation for application of the proposed wire electrochemical micro-machining.

One cavitation structure that the channel cross section expanded suddenly was introduced in single straight microchannel. The experiment was carried out with R-134a as the fluid medium, which was drove by gear pump. The flow pattern was observed by CCD and microscope. The average boiling heat transfer coefficient was estimated with the calculation method proposed in this paper. The experimental results present the boiling began at the cavitation structure, and stable flow boiling was maintained. When heat power grew up the boiling became strong then the pressure drop in the micro-channel increased and the heat transfer was enhanced. The liquid percentage in two-phase flow increased and the length of boiling area became small when mass flux grew up with the fixed heat power.

Electro-pulse spraying (EPS) is the coating technology of “electric explosion of conductive materials” when high-voltage and powerful impulse flows through a wire conductor. Object of our investigation — tribological properties of sliding pairs with copper micro-coats made by EPS after one time explosion. Small-grained dense structure coat with evaluated thickness about 4–6 ?m was obtained. Tribological tests, performed at marginal lubrication with multi-stage load, shows that using EPS-specimens the value of friction coefficient is lower as control version. At instantaneous setting of load for long-term running the copper films adopts well to the change of load. The wear of friction pairs according to worn mass show that EPS-specimens worn 79% less than CV-specimens. The investigations point out that copper micro-coats have better tribological properties comparing to control version of friction pairs.

This study investigated the magnetic effects on the nano-ferrofluid within a closed loop heat pipe (LHP) without any micro-structure. The results show the enhancement of the thermal performance of the LHP can be achieved by setting the magnets properly.

Antifreeze proteins (AFPs) allow biological organisms, including insects, fish, and plants, to survive in freezing temperatures. While in solution, AFPs impart cryoprotection by creating a thermal hysteresis (TH), imparting ice recrystallization inhibition (IRI), and providing dynamic ice shaping (DIS). To leverage these ice-modulating effects of AFPs in other scenarios, a range of icing assays were performed with AFPs to investigate how AFPs interact with ice formation when tethered to a surface. In this work, we studied ApAFP752, an AFP from the beetle Anatolica polita, and first investigated whether removing the fusion protein attached during protein expression would result in a difference in freezing behavior. We performed optical microscopy to examine ice-crystal shape, micro-structure, and the recrystallization behavior of frozen droplets of AFP solutions. We developed a surface chemistry approach to tether these proteins to glass surfaces and conducted droplet-freezing experiments to probe the interactions of these proteins with ice formed on those surfaces. In solution, ApAFP752 did not show any DIS or TH, but it did show IRI capabilities. In surface studies, the freezing of AFP droplets on clean glass surfaces showed no dependence on concentration, and the results from freezing water droplets on AFP-decorated surfaces were inconclusive.