Academic literature on the topic 'Load Modulated Array'
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Journal articles on the topic "Load Modulated Array"
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Sivasubramanian, Gobi Mohan, and Murali Narayanamurthy. "Implementation of PWM AC chopper controller for capacitor run induction motor drive via bacterial foraging optimization algorithm." International Journal of Reconfigurable and Embedded Systems (IJRES) 9, no. 3 (November 1, 2020): 169. http://dx.doi.org/10.11591/ijres.v9.i3.pp169-177.
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<p>This paper focuses on design of closed-loop control for pulse width modulated AC chopper controlled capacitor run induction motor drive engaging enriched optimization algorithm based on foraging of bacteria. Capacitor run induction motor is a non-linear device and its parameter varies under different functional point of the system. A linearized increment model for PWM AC chopper is illustrated for a particular functional point of the drive. The conventional method does not provide acceptable performance under different load conditions. Bacteria foraging optimization technique categorizes accurate control parameters for the superlative dynamic response under unit step load variations. Field Programmable Gate Array is implemented practically for a particular functional point of the drive to exhibit accurate performance. Experimental and simulated results are obtained to authenticate the effectiveness of the optimized controller.</p><p> </p>
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Dibiase, Marco, and Luca De Marchi. "An Optimal Shaped Sensor Array Derivation." Micromachines 14, no. 6 (May 30, 2023): 1154. http://dx.doi.org/10.3390/mi14061154.
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In Structural Health Monitoring (SHM) applications, the Direction of Arrival (DoA) estimation of Guided Waves (GW) on sensor arrays is often used as a fundamental means to locate Acoustic Sources (AS) generated by damages growth or undesired impacts in thin-wall structures (e.g., plates or shells). In this paper, we consider the problem of designing the arrangement and shape of piezo-sensors in planar clusters in order to optimize the DoA estimation performance in noise-affected measurements. We assume that: (i) the wave propagation velocity is unknown, (ii) the DoA is estimated via the time delays of wavefronts between sensors, and (iii) the maximum value of the time delays is limited. The optimality criterion is derived basing on the Theory of Measurements. The sensor array design is so that the DoA variance is minimized in an average sense by exploiting the Calculus of Variations. In this way, considering a three-sensor cluster and a monitored angles sector of 90°, the optimal time delays–DoA relations are derived. A suitable re-shaping procedure is used to impose such relations and, at the same time, to induce the same spatial filtering effect between sensors so that the sensor acquired signals are equal except for a time-shift. In order to achieve the last aim, the sensors shape is realized by exploiting a technique called Error Diffusion, which is able to emulate piezo-load functions with continuously modulated values. In this way, the Shaped Sensors Optimal Cluster (SS-OC) is derived. A numerical assessment via Green’s functions simulations shows improved performance in DoA estimation by means of the SS-OC when compared to clusters realized with conventional piezo-disk transducers.
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He, Ren, and Junmin Li. "Optimized design and performance analysis of a magnetic-field modulated brushless dual-mechanical port motor with Halbach array permanent magnets." Advances in Mechanical Engineering 12, no. 9 (September 2020): 168781402095775. http://dx.doi.org/10.1177/1687814020957754.
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In order to develop an electrical continuously variable transmission (E-CVT) to replace mechanical power coupling equipment applied in series-parallel hybrid electric vehicle (HEV), this paper proposes a magnetic-field modulated brushless dual-mechanical port motor with Halbach array permanent magnets, which has a more compact structure. The operating characteristics are analyzed by the lever analogy. It is concluded that the motor can realize the speed and torque decoupling between the engine and the wheel, which meet multi-mode operation requirements for HEV. To realize the multi-objective design of torque output, torque ripple and usage amount of permanent magnets, an optimization scheme combined parameter sensitivity with response surface methodology is adopted. The trade-offs among the optimization objectives are considered, then the key structural parameters and its optimal values are efficiently determined. Based on a two-dimensional model, the electromagnetic performances are simulated and analyzed. The results show that, after the parameters optimization, the no-load back electromotive force (EMF) has better sinusoidal characteristic, and the torque ripples and cogging torque peaks of the motor have been significantly reduced. Furthermore, a prototype motor is tested. The experimental results are consistent with the simulation results, which demonstrates the validity of the proposed structure and parameter optimization method.
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Ishaq, Muhammad, Yanbo Che, and Kifayat Ullah. "Switching Regulation in the Control of 5-Phase Permanent Magnet Synchronous Motor Fed by 3×5 Direct Matrix Converter." European Journal of Electrical Engineering 23, no. 1 (February 28, 2021): 27–35. http://dx.doi.org/10.18280/ejee.230104.
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Matrix converter is an AC-AC direct power converter comprising of an array of bi-directional switches. It does not require an intermediate DC-link and allows sinusoidal output waveforms with varying amplitudes and frequencies. The configuration of these bi-directional switches decides the number of inputs and outputs of the matrix converter. This research uses a direct matrix converter (DMC) as a phase-changing device that can convert a three-phase AC voltage into a 5-phase AC voltage. The DMC is modulated with the model predictive control algorithm. The output of DMC is fed to a five-phase permanent magnet synchronous motor (PMSM). The model predictive current control technique for DMC is carried out by developing a mathematical model of an input filter and PM motor used as a load. The predictive control of DMC results in sinusoidal output current, and it also enables the frequency variation in the output current. This frequency variation is useful in controlling the speed of the motor connected to the load. After controlling the 5-phase motor, the switching frequency regulation is done to observe its effect on the motor's stator current waveforms. Switching frequency regulation helps to limit the unnecessary switching of DMC. We developed a MATLAB-based Simulink model to study PMSM, and detailed results are presented. The results show that switching regulation can significantly reduce the switching frequency without compromising the current waveform quality.
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Sedaghat, Mohammad A., Vlasis I. Barousis, Ralf R. Müller, and Constantinos B. Papadias. "Load modulated arrays: a low-complexity antenna." IEEE Communications Magazine 54, no. 3 (March 2016): 46–52. http://dx.doi.org/10.1109/mcom.2016.7432147.
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Morgan, Helen M., Christoph Klein, Stephan G. Boehm, Kimron L. Shapiro, and David E. J. Linden. "Working Memory Load for Faces Modulates P300, N170, and N250r." Journal of Cognitive Neuroscience 20, no. 6 (June 2008): 989–1002. http://dx.doi.org/10.1162/jocn.2008.20072.
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We used event-related potential (ERP) methodology to examine neural activity associated with visual working memory (WM) for faces. There were two main goals. First, to extend previous findings of P300 load modulation to WM for faces. Second, to examine whether N170 and N250r are also influenced by WM load. Between one and four unfamiliar faces were simultaneously presented for memory encoding. After a 1-sec delay, a target face appeared, and participants had to judge whether this face was part of the previous face array. P300 amplitude decreased as WM load increased, and this P300 suppression was observed at both encoding and retrieval. WM load was also found to modulate other ERPs. The amplitude of the N170 elicited by the target face decreased with load, and this N170 decrease leveled off at load 2, reflecting the behavioral WM capacity of around two faces. In addition, the N250r, observed as an ERP difference for target faces that were present in the encoding array relative to target faces that were absent, was also reduced for higher WM loads. These findings extend previous work by showing that P300 modulation by WM load also occurs for faces. Furthermore, we show, for the first time, that WM load affects the N250r and the early visual N170 component. This suggests that higher visual areas play an important role in WM for faces.
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Bhat, Sandeep, and Ananthanarayanan Chockalingam. "Precoding for Multiuser Load-Modulated Arrays on the Downlink." IEEE Communications Letters 22, no. 9 (September 2018): 1774–77. http://dx.doi.org/10.1109/lcomm.2018.2849079.
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Bhat, Sandeep, and A. Chockalingam. "LSE Precoder for Load Modulated Arrays With Channel Modulation." IEEE Wireless Communications Letters 9, no. 8 (August 2020): 1295–99. http://dx.doi.org/10.1109/lwc.2020.2989134.
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Ullmann, Amy, Marc Dolan, Erol Fikrig, Joseph Piesman, and Nordin Zeidner. "Immunization with Adenoviral-expressed salivary gland proteins (SALPs) decreases spirochete load in a murine model of Lyme borreliosis (52.2)." Journal of Immunology 184, no. 1_Supplement (April 1, 2010): 52.2. http://dx.doi.org/10.4049/jimmunol.184.supp.52.2.
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Abstract It is known that tick saliva contains a vast array of proteins that function as anti-haemostatic, anti-inflammatory, and immunomodulatory factors when delivered to the vertebrate host. Previous studies have also demonstrated that prior exposure to tick saliva induced specific immunity to tick infestation, as well as affording protection against tick-transmitted Borrelia burgdorferi infection in the mammalian host. In our current studies we explored a vaccination technique to modulate tick feeding, using an adenovirus (Ad) expression system to deliver four salivary proteins (previously shown to modulate host immunity) derived from Ixodes scapularis; Salp15, Salp25A, Salp25D, and ISAC. C3H/HeJ mice were immunized individually with Ad-Salp15 and Ad-ISAC constructs, as well as all four constructs simultaneously. Immunized mice were then challenged with B. burgdorferi-infected I. scapularis ticks. Utilizing quantitative PCR, spirochete burden in target organs like heart and bladder was reduced by 55% compared to animals immunized with an empty Ad-cassette. The generation of anti-salivary protein antibodies in a murine model was also confirmed. Our results indicate that adenovirus expressed tick salivary proteins can stimulate dendritic cell expression of tick salivary proteins, as well as tick-specific humoral and cellular immune responses in mice, affording at least partial protection against subsequent tick-transmitted B. burgdorferi infection.
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Verma, Rakesh, Kartik Sehgal, Lin Zhang, Mehmet H. Kocoglu, Kavita Dhodapkar, and Madhav V. Dhodapkar. "Enrichment Of Embryonal Stem Cell Signature and Persistent Genomic Complexity In Residual Disease Following Pomalidomide Therapy In Myeloma." Blood 122, no. 21 (November 15, 2013): 4200. http://dx.doi.org/10.1182/blood.v122.21.4200.4200.
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Abstract Current therapy of myeloma including combination with IMID(R) immunomodulatory agent such as pomalidomide (POM) leads to high rates of clinical responses in patients with advanced multiple myeloma without translating to cures. Therefore, there is a need to better characterize the nature of residual disease after anti-myeloma therapy. POM has shown clinically promising efficacy in relapsed myeloma but nearly all patients eventually progress. In order to better understand the nature of residual disease, we compared baseline CD138+ myeloma tumor cells from 3 patients with those remaining after completing 2 cycles of therapy with POM (2-4 mg/day) and dexamethasone (40 mg/week). CD138+ plasma cells were isolated from the bone marrow before and after POM therapy and analyzed with gene expression profiling (GEP), and whole exome sequencing (WES). Principal component analysis (PCA) on the GEP data (pre vs. post POM treatment) revealed that in contrast to baseline samples, the ones with residual disease were clustered together, and this was further confirmed with unsupervised hierarchical clustering. Analysis of differentially expressed genes revealed nearly 600 differentially modulated genes, including some involved in the immune system regulation, inflammatory pathways and stem cells. Gene set enrichment analysis (GSEA) identified enrichment of distinct gene-sets/pathways including- transcriptional targets regulated by core embryonal stem (ES) cell factors SOX2 and NANOG. Analysis of genes in the core ES signature (Nat Genet. 2008; 40: 499) revealed that nearly 80% of these ES genes were enriched in the residual disease after treatment with POM. Whole exome sequencing has emerged as a powerful tool to dissect the genomic complexity in cancer. Genomic DNA from bone marrow derived CD138+ tumor cells before and after POM therapy was captured on the NimbleGen 2.1M human exome array and subjected to 74 base paired-end reads on the Illumina HiSeq instrument as described previously (Proc Natl Acad Sci U S A. 2009; 106:19096). Sequence reads were mapped to the reference genome (hg19) using the ELAND program. Reads outside the targeted sequences were discarded and statistics on coverage were collected from the remaining reads using perl scripts. ELAND was also used for indel detection. For matched normal/germline and CD138+ tumor pairs, somatic mutations were called by comparing reference and non-reference reads from the matched pair by Fisher’s exact test with tumor-specific thresholds determined from approximation of the null distribution. WES analysis of baseline (pre therapy) samples identified a median of 36 protein altering coding mutations per sample. Importantly, the degree of mutational load was very comparable between baseline and residual disease (post therapy), and nearly 80% of the mutations detected in the residual disease were also observed at baseline. These data suggest that residual disease following therapy in myeloma is characterized by high level of genomic complexity similar to that observed at baseline. However in spite of the genetic heterogeneity and complexity at baseline, the residual CD138+ plasma cells converge to a distinct signature enriched in a transcriptional program associated with embryonal stem cell genes known to be targets of SOX2 and NANOG. Drug resistant/residual CD138+ tumor cells in myeloma therefore show transcriptional profiles previously implicated in cancer stem cells. Targeting stemness-associated genes may be essential to effectively treat residual disease in myeloma. Disclosures: No relevant conflicts of interest to declare.
Dissertations / Theses on the topic "Load Modulated Array"
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Bhat, Sandeep. "Load Modulated Arrays for Multi-antenna Wireless Communications." Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4422.
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Conventional multi-antenna transmitters use a separate RF chain (consisting of DACs, mixers, filters) and a power amplifier (PA) for each antenna element, and use modulation alphabets such as QAM/PSK for transmission. The consequences of this are, first, the RF hardware complexity, size, and cost increase with the number of antennas, and second, the linearity requirements for higher order QAM and OFDM transmissions affect the power efficiency of the amplifier in each RF chain. Load modulated array (LMA) is emerging as a promising multi-antenna transmission architecture that alleviates the aforementioned issues. An LMA uses a single central power amplifier (CPA) for the entire antenna array and no RF chains. LMA is based on the concept of load modulation, in which an antenna current proportional to the information bearing signal is achieved by modulating the antenna load impedances, while maintaining the amplifier input at a constant level. Varying the antenna load impedances with the information signal can cause a mismatch between the source impedance and the effective antenna impedance, causing power reflection into the CPA. A way to mitigate this is to ensure that the transmit signal in every channel use lies on the surface of a multidimensional hypersphere. This is called ‘phase modulation on the hypersphere (PMH)’. In this thesis, we investigate PMH signaling, detection, and precoding for LMAs in point-to-point, multiuser uplink, and multiuser downlink communication scenarios.
In the first part, we consider the construction of PMH signal vectors for LMAs. Construction of PMH signal vectors is typically non-analytic (e.g., clustering, potential maximization) and hence becomes computationally and storage wise expensive. We propose random phase modulation (RPM) as an inexpensive means of constructing PMH signal vectors. The idea of RPM is extended to random phase precoding (RPP) and precoder index modulation (PIM) to devise PMH signaling schemes that achieve good performance. Indexing in time and spatial domains is also investigated.
In the second part, we consider LMAs for communication in multiuser scenario. For multiuser communication on the uplink, we show using analysis and simulations that LMAs achieve superior bit error performance compared to other single RF chain multi-antenna transmission architectures in the literature. To exploit this performance advantage in large systems, we propose low complexity multiuser signal detection algorithms based on message passing and Monte Carlo sampling techniques. For multiuser communication on the downlink, we design a block diagonalizing precoder that nulls multiuser interference at the user terminals while ensuring that the precoded signal vector lies on the hypersphere. Further, when the antenna load impedances are tuned using discrete values from a finite set, the support of the precoded signal vector is finite. For this setting, we propose an iterative precoding algorithm using the generalized least square error (GLSE) framework.
In the final part, we propose a hybrid signaling scheme using LMAs and channel modulation (CM), wherein additional information bits are conveyed through the ON/OFF status of parasitics placed near the antenna array. For this scheme, we exploit the inherent sparsity in the signal vectors for multiuser detection on the uplink. We also incorporate CM in the GLSE framework for multiuser precoding on the downlink.
Conference papers on the topic "Load Modulated Array"
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Bhat, Sandeep, and A. Chockalingam. "Random phase modulation in load modulated arrays." In 2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). IEEE, 2017. http://dx.doi.org/10.1109/pimrc.2017.8292220.
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Anthon, D. W., A. T. Eggleston, S. G. Grubb, J. G. Kwasegroch, P. A. Leilabady, and D. L. Sipes. "Diode-pumped solid-state lasers for telecommunication applications." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.tut1.
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Externally modulated solid-state lasers are increasingly used for analog fiber-optic applications such as cable television. The solid-state laser functions as an active filter for a laser diode array, converting its output to the required diffraction-limited, high power, low noise output. The main concerns in these systems are thermal management and diode lifetime. The two issues are closely related; 10°C of thermoelectric cooling can double both the diode lifetime and the system heat load. Diode lifetimes can also be enhanced by reducing the diode current. Increased Nd laser efficiency addresses all these issues. Recent work with Nd:YLF has shown a 40% optical-to-optical conversion efficiency at 1313 nm, 20% better than for Nd:YAG at 1319 nm. This suggests the possibility of ESA in Nd:YAG. Optimized focussing optics and laser rod length improved the performance of Nd:YLF at both 1313 and 1047 nm. The latter device has exhibited optical-to-optical conversion efficiencies of more than 55%. It has been used in telecommunication systems as a pump for high-power Yb,Er phosphosilicate fiber amplifiers. Outputs of more than 200 mW have been obtained at 1536 nm. This device is useful as a power amplifier, especially in analog fiber-optic systems.
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Bhat, Sandeep, and A. Chockalingam. "Load Modulated Arrays Using Channel Modulation with RF Mirrors." In 2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring). IEEE, 2019. http://dx.doi.org/10.1109/vtcspring.2019.8746397.
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Bhat, Sandeep, and Ananthanarayanan Chockalingam. "MCMC Sampling Based Signal Detection in Multiuser Load Modulated Arrays." In 2018 IEEE 87th Vehicular Technology Conference (VTC Spring). IEEE, 2018. http://dx.doi.org/10.1109/vtcspring.2018.8417493.
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Baker, Brendon M., Roshan P. Shah, and Robert L. Mauck. "Dynamic Tensile Loading Improves the Mechanical Properties of MSC-Laden Aligned Nanofibrous Scaffolds." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19447.
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Fibrocartilaginous tissues such as the meniscus and annulus fibrosus serve critical load-bearing roles, relying on arrays of highly organized collagen fibers to resist tensile loads experienced with normal physiologic activities [1]. As these specialized structures are often injured, there exists great demand for engineered tissues for repair or replacement. Towards recreating the structural and mechanical features of these anisotropic tissues in vitro, we fabricate scaffolds composed of co-aligned, ultra-fine biodegradable polymer fibers. These 3D micro-patterns direct mesenchymal stem cell (MSC) orientation and the subsequent formation of organized extracellular matrix (ECM) [2]. As this cell-produced matrix continually develops with time in culture, the mechanical properties of the construct gradually increase. In previous studies aimed at engineering human meniscus tissue, constructs achieved moduli of ∼40MPa after 10 weeks of culture, representing a two-fold increase in the starting properties of the scaffold [3]. Despite this demonstrable increase, this value remains well below that of the native tissue. As mechanical forces are essential to the maintenance of musculoskeletal tissues, this work examined the effect of cyclic tensile loading on MSC-laden nanofibrous constructs to enhance their in vitro maturation. We hypothesized that this loading modality would modulate the transcriptional behavior of seeded MSCs, spur the deposition of collagen-rich matrix, and lead to additional improvements in construct mechanical properties.
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Livescu, G., L. M. F. Chirovsky, T. Mullally, and Arza Ron. "Gigabit per second switching of smart pixel receiver-transmitter pairs." In Photonics in Switching. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/ps.1995.pfb6.
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Smart pixels are opto-electronic circuits with optical input/output and electronic logic circuits for complex functionality [1]. Arrays of smart pixels can control two dimensional arrays of light beams in high speed, high throughput free space photonic switching systems [2]. An example are the 4x4 arrays of 2x1 embedded control routing nodes, based on GaAs/AlGaAs field-effect-transistor self-electrooptic-effect device (FET-SEED) technology [3], recently used in a five stage switching system [4]. Although this system was operated at 155Mbit/s only, the speeds of smart pixels can be made much higher. One way to achieve increased speeds is by addition of gain stages and the use of larger FETs. However, this makes the receivers and transmitters larger and more dissipative. Another way to increase the switching speed is to use short pulses as optical inputs, which, according to theory [5], considerably reduces the switching time of the receivers. Simple receivers have, indeed, been demonstrated to operate up to 1Gbit/s [6], but receiver-transmitter pairs could only operate up to 650Mbit/s [7]. The speed of the pair was limited by the performance of the transmitter used, which consisted of a FET inverter driving the common node of two modulators connected in series. One can make a faster transmitter by eliminating the load FET and one of the modulators, thus reducing the capacitance and increasing the effective charging current of the modulator. With such a transmitter, and the use of mode-locked pulses in the AROEBICS (Asynchronous Reset On Every Bit for Input Contentionless Switching) method [8], 200ps switching times were recently obtained [9,10]. This result indicated that smart pixels containing this transmitter should be capable of operating in the GHz range. In the present work we use trains of mode-locked laser pulses separated by 1ns to demonstrate the 1GHz operation of a receiver-transmitter pair.