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The design of coating structure is an important method to achieve the favorable absorbing capability. For the issues in the computer-aided design of cpating structure, such as low operation efficiency, optimization of single target and manual intervention, a multi-objective optimization model of radar absorbing coating with the aim of “thin-layer, light-weight, broad-band and strong-absorbing” is constructed, and an optimized project based on NSGA-Ⅱis presented. The optimized thickness of the double-layer absorbing coating composing of 3# and 2# materials is 0.6 mm with the reflectance of lower than -8 dB at 18~18 GHz band. Experiments show that this method can be used for the structure design of multilayered radar absorbing coating in case of prediction of redundancy. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The air-core pulsed alternator has been studied for more than three decades. However, its optimized design theories are still rarely reported. The performance of the air-core pulsed alternator-based pulsed-power system is often closely associated with the electrical machine parameters, the system structure, and the load requirements. The parametric optimization of this type of alternator has a very important influence on the performance. This paper focuses on the optimization theory of the air-core pulsed alternator design, including the optimization of the magnetic field distribution, the turn number of armature winding, and the turn number of field winding. The features of the magnetic field distribution in the air-core pulsed alternators are analyzed based on the analytical expressions. By designing a ferromagnetic shield put on the outside of the stator, the radial magnetic field component increases and the circumferential one decreases. The optimization principles of the winding turn numbers are also deduced based on the system circuit and operation mode. The optimization theories are verified by system-level dynamic simulation. Finally, some rules are summarized, which are beneficial to the optimized design of the air-core pulsed alternator. [ABSTRACT FROM PUBLISHER]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper studies constructing polynomial Bézier surface that interpolates a Bézier curvilinear quadrilateral as boundary geodesics. The construction consists of two parts. First, from the given corner data (i.e., position, tangent and curvature at the corner of each curve), four quintic Bézier curvilinear quadrilateral with minimum strain energy is constructed to satisfy the constraints of the crossing geodesics on a surface. Second, a polynomial Bézier surface of degree (7, 7) is constructed to interpolate the quadrilateral as boundary geodesics of the constructed surface. We identify the precise degrees of freedom in terms of the control points. And the constructed surface that adheres to the NURBS standard and employs geometric shape handles can be readily incorporated into commercial CAD systems. The method is illustrated by several computational examples. [ABSTRACT FROM AUTHOR]

In order to meet the requirement of high sensitivity and signal-to-noise ratios (SNR), this study develops and optimizes a piezoresistive pressure sensor by using double silicon nanowire (SiNW) as the piezoresistive sensing element. First of all, ANSYS finite element method and voltage noise models are adopted to optimize the sensor size and the sensor output (such as sensitivity, voltage noise and SNR). As a result, the sensor of the released double SiNW has 1.2 times more sensitivity than that of single SiNW sensor, which is consistent with the experimental result. Our result also displays that both the sensitivity and SNR are closely related to the geometry parameters of SiNW and its doping concentration. To achieve high performance, a p-type implantation of 5 × 1018 cm−3 and geometry of 10 µm long SiNW piezoresistor of 1400 nm × 100 nm cross area and 6 µm thick diaphragm of 200 µm × 200 µm are required. Then, the proposed SiNW pressure sensor is fabricated by using the standard complementary metal-oxide-semiconductor (CMOS) lithography process as well as wet-etch release process. This SiNW pressure sensor produces a change in the voltage output when the external pressure is applied. The involved experimental results show that the pressure sensor has a high sensitivity of 495 mV/V·MPa in the range of 0–100 kPa. Nevertheless, the performance of the pressure sensor is influenced by the temperature drift. Finally, for the sake of obtaining accurate and complete information over wide temperature and pressure ranges, the data fusion technique is proposed based on the back-propagation (BP) neural network, which is improved by the particle swarm optimization (PSO) algorithm. The particle swarm optimization–back-propagation (PSO–BP) model is implemented in hardware using a 32-bit STMicroelectronics (STM32) microcontroller. The results of calibration and test experiments clearly prove that the PSO–BP neural network can be effectively applied to minimize sensor errors derived from temperature drift.

Highlights: [•] Photovoltaic conversion of sunlight is promising as a carbon-free-energy-source. [•] An optimized multi-junction photovoltaic cell was attempted and reached. [•] 58% efficiency can be reached with five junctions. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) based power semiconductors are expected to contribute to an increase in inverter efficiency, switching frequencies, maximum permissible junction temperature, and system power density. This paper presents a comparison of silicon (Si) and SiC device technologies for the use in hybrid electric vehicle traction inverters. SiC-JFETs and SiC-MOSFETs are characterized and a scalable loss and scalable thermal modeling approach is used to find the optimum chip area for each Si or SiC traction inverter. This procedure also provides a proper technical comparison of the semiconductor technologies. The progressed simulations using standardized drive cycles and thermal-electrical coupled semiconductor models permit an inverter performance evaluation close to real load situations, leading to an improved estimation of the benefit which can be expected from systems utilizing SiC technology. This paper concludes that the SiC devices can lead to a reduction in chip area and semiconductor losses by more than 50% at the same time in hard switching applications with partial load dominated mission profiles. [ABSTRACT FROM AUTHOR]

A novel route discovery and maintenance algorithm is proposed for solving the packet lost rate and end-to-end delay problem of Dynamic Source Routing (DSR) during the interval between the old source route and new source route in Mobile Ad Hoc Network (MANET), which is aimed to optimize the performance of route protocol. The proposed algorithm first defines two concepts, battery power and received signal power, both of which are used to measure the statement of any node and link respectively. Then route discovery and maintenance algorithm are modified to make the DSR possess the function of threshold judgment. Finally the relation between performance of packet deliver fraction and end-to-end delay of enhanced DSR (EDSR) and the number of nodes and mobile velocity is simulated by network software. The simulation results show that packet deliver fraction and end-to-end delay of EDSR is better than that of DSR when the number of nodes is higher than 150 or velocity of node is lower than 10 m/s. What's more, the performance of EDSR is equal to that of DSR in other region. For the reasons above, compared with DSR, the performance of proposed EDSR protocol is better obviously. It provides an important reference for low-speed of large-scale MANET routing protocol. [ABSTRACT FROM AUTHOR]

The Two-Dimensional Discrete Cosine Transform / Inverse Discrete Cosine Transform (2-D DCT/IDCT) is a key algorithm in image and video coding applications. Therefore, the optimization of its hardware implementation requires low complexity design. For this purpose, a possible solution is to avoid multiplications and to replace them by additions and shifts, while meeting the requirement of real time applications. In this paper, an optimized design for a multiplierless hardware implementation of fast 2-D DCT/IDCT based on modified Loeffler algorithm is achieved, in which a new approach is used to reduce the amount of additions and shift operators. This approach is based on the combination of three representations of constant coefficient multiplications: natural binary, canonic signed digit (CSD) and a new signed digit representation. The optimized 1-D DCT/IDCT design is developed, by selecting for each constant coefficient multiplication the suitable representation method that allows simultaneously a maximum frequency operation and a minimum number of additions and shift operators. The hardware implementation of 2-D DCT/IDCT is performed with the optimized 1-D DCT/IDCT design and a robust transpose buffer. All these pipelined hardware implementations are described in VHDL hardware language, synthesized and implemented on low cost FPGA. This proposed 2-D DCT/IDCT design reduces the computational complexity compared to other previous designs. The implementation results of the proposed 2-D DCT/IDCT show an increase of the maximum frequency by 14% and a decrease of resources usage by 18.5% in comparison with previous design based on modified Loeffler algorithm. [ABSTRACT FROM AUTHOR]

Highlights: [•] Whole mathematical model of Vibration Isolation System (VIS) in DRLG IMU is built. [•] An effective design method of VIS based on motion decoupling is proposed. [•] Six degree of freedom (DOF) model of VIS is decoupled into six one DOF models. [•] Stiffness and damping parameters are optimized to meet the precision requirement. [•] A veritable VIS used in DRLG POS is developed as an instance. [ABSTRACT FROM AUTHOR]

The saving and re-use of energy has acquired great relevance in recent years, being of great importance in the automotive sector. In the literature, it is possible to find different proposals for energy-harvesting damper systems (EHSA)-the electromagnetic damper being a highly recurrent but still poorly defined proposal. This article specifically focuses on studying the concept and feasibility of an electromagnetic suspension system that is capable of recovering energy, using a damper formed by permanent magnets and a system of coils that collect the electromotive force generated by the variation of the magnetic field. To study the feasibility of the system, it is necessary to know the maximum energy that can be recovered through the winding system; however, the difficulties in obtaining the derivative of the magnetic flux and its derivative for each position make the analytical method very tedious. This paper presents an experimental method with which to maximize energy recovery by defining the optimum relative position between magnet and coil.

To improve covariate balance over a complete randomization, a number of methods have been proposed recently to utilize modern computational capabilities to find allocations with balance in observed covariates. Asymptotic inference on treatment effects based on these designs is more complicated than that under complete randomization, and this is why Fisher randomization tests often are suggested. This article suggests model-based Bayesian inference as a general method of inference in these designs, which can deal with complications such as arbitrary covariate balancing criteria and complex estimands. As an illustration, we focus on the case when the outcome is linearly related to the covariates and the estimand of interest is the Sample Average Treatment Effect (SATE). We use a large Monte Carlo simulation to compare the finite sample performance of the model-based Bayesian inference with that of two previous methods which are valid for asymptotic inference of SATE under Mahalanobis distance based rerandomization. We find that for experiments with small to moderate sample sizes, Bayesian inference is to be preferred to the previous methods. As a byproduct, we also find that regression adjustment together with small sample adjusted estimators of standard errors perform better than the previous methods., (© 2022 John Wiley & Sons Ltd.)

Abstract: According to the analysis of different discontinuous images of target, the precision of the images can be increased for lidar imaging, and the deviation of the variation of the vertical and horizontal distance between targets has been analyzed. The laser divergence angle has been briefly analyzed under the laser arrays for realistic measurements and also gave the image restoration of target. [Copyright &y& Elsevier]

The motion compensation based on ring laser gyroscope (RLG) position and orientation system (POS) is a key technology to improve the imaging quality and efficiency of airborne Earth observation system. However, RLG POS faces great problems in the vibration environment, where the mechanical dither of RLG causes the adverse disturbance to inertial measurement unit (IMU) which should be eliminated, and the external vibration must be accurately measured with high bandwidth and low noise. To solve the problem, a kinetics model of RLG IMU is established based on a vibration response mechanism in this paper. An optimized design method of mechanically dithered RLG IMU with a vibration-damping system is proposed that can reduce the measurement error. In addition, the size-effect error and optimization method of RLG IMU are analyzed. Based on finite-element analysis software, a high-precision mechanically dithered RLG POS is designed and developed to be used in various imaging payloads. The experimental results show that the inertial navigation errors of RLG POS are 0.196 (\sigma), 0.659 (\sigma), and 0.707 kn (\sigma) for static, vehicle, and airborne experiments, respectively. It contributes to realize high-quality image of airborne interferential synthetic aperture radar and 1 : 500 scale map of camera without ground control marks. The precision of developed RLG POS is close to that of the most advanced production POS/AV610. [ABSTRACT FROM PUBLISHER]

Abstract: A numerical design model is presented for the polymer waveguide in an electro-optic modulator. The effective index method is used to analyze the height of the core waveguide and rib waveguide, an improved Marcatili method is presented to design the rib waveguide width in order to keep the strong single mode operation and have a good match with the standard fiber. Also, the thickness of the upper cladding layer is discussed through calculating the effective index of the multilayer planar waveguide structure has been obtained by setting the optical loss due to the metallic absorption to an acceptable value (<0.1dB/cm). As a consequence, we take the EO polymer waveguide structure of UV15:CLD/APC:UFC170 as an example, an optimized design is reported. [Copyright &y& Elsevier]

This paper is the numerical investigation reports about field characteristic of fan section. First, it presents the control equations and boundary conditions for numerical simulation. Then the details of numerical results are given about velocity characteristics of fan section in 0.55mX0.4m low turbulence aero- acoustics wind tunnel. Conclusion could be got that numerical methods used could give rational results comparing with experiment data. Then, basing on the flow around rotor and stator, the flow mechanism inside fan section was analyzed. At last different fan models were study based on the numerical results. These parameters imposed influence on performance and flow mechanism of fan including the distance between rotor and stator, stator swept and leaned. Stator leaned could significantly reduce or eliminate rotor wake and tip separation, and could produce a more uniform velocity profile at exit. Conclusions state the importance and feasibility of CFD in aerodynamical design of fan section in wind tunnel. [ABSTRACT FROM AUTHOR]

This article is focused on the dynamical strength analysis and design optimization of a pipe-joint system. A three-dimensional model of a fuel pipe-joint system is established and the strength and dynamic analysis of the system under the pressure impact load is analysed. In order to avoid dangerous forced vibrations or resonance, and to lower vibration level, the clamps’ numbers and locations are optimized. The results show that: (a) under the pressure impact load, near the T-branch pipe, clamps and elbows, the pipe system’s failure can easily occur; and (2) the numbers and locations of clamps of pipe-joint system can be optimized and the optimized pipe-joint system has better anti-vibration ability. [ABSTRACT FROM AUTHOR]

In this article, the optical properties of the multilayer films of SiO2/W/SiO2 for solar selective absorber fabricated by sputtering deposition are simulated and fabricated. The optical properties of the multilayer films with the various layer thicknesses are studied. And the relationships between the film thickness and the optical reflectance are found. An area of the contour map of the optimized photo-thermal conversion efficiency (PTCE) more than 92% for solar selective absorber layer is found. One SiO2/W/SiO2 multilayer film with the thickness of 96/7/87 nm that has the maximum PTCE of more than 94% is simulated and fabricated. [ABSTRACT FROM AUTHOR]

A multichannel thin-film sensor is implemented from a set of microstrip-coupled split-ring resonators (SRRs) with different dimensions. Each SRR exhibits a unique high-Q resonance that is sensitive to the presence of a sample in a particular area. Hence, this SRR-based sensor can function (i) to detect different samples simultaneously to increase the throughput or (ii) to characterise nominally identical samples at multiple frequencies to increase the sensor selectivity. In addition, the sensitivity of this SRR-based sensor is optimized through strategic design of the resonator shape to produce a strong confined electric field at each sensing region. The design principle is validated with simulation and measurement. Owing to the optimized design, sensing a low-permittivity film with a thickness as small as one thousandth of the operating wavelength is achievable. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, the yearly performance of a library building located in Harbin, China, equipped with a ground-coupled heat pump (GCHP) system, was simulated and its ground heat exchanger (GHE) was designed in the TRNSYS 17 environment. Utilizing the hourly load simulation results, a TRNSYS model was developed to analyze underground thermal balance of the entire system, obtaining the 30-year operation conditions of the reference building. According to simulation results, annual average storage temperature, the highest and lowest inlet temperature of the heat pump, factors that influence efficiency of the system, change as the number of boreholes changes. And the optimized length of heat exchangers was studied, as well as method of determining the concentration of antifreeze in heat-transfer fluid in cold regions. [Copyright &y& Elsevier]

Abstract: Sandwich Pipes (SPs) have been developed to overcome the required flow assurance and pressure capacity issues in deep and ultra-deep waters. This research aims at studying the influence of certain structural parameters on the pressure capacity (also referred to as the plastic buckling pressure) of Sandwich pipelines. The use of high grade steel pipes, as the internal or external pipes, has also been considered as one of the design parameters in this study. Moreover, a comprehensive parametric study, considering a practical range of the parameters that influence the response of SPs (and considering 3840 SP configurations) was conducted. The results from this large array of pipes were used to formulate a practical equation, capable of estimating the plastic buckling pressure of SPs. The accuracy of the proposed equation was evaluated by comparing the results with the experimental and numerical results available in the literature. The comparative results demonstrated that the proposed equation could predict the buckling capacity of such pipes with a reasonable accuracy. Furthermore, the proposed equation was used, along with a general optimization procedure, to establish the most optimum and cost-effective combination of structural parameters for SPs suitable for use in various water depths. [Copyright &y& Elsevier]

Abstract: The purpose of the present paper is to study the X-ray energy utilization efficiency that is inherent in the improved design of actual X-ray digital imaging systems in industrial applications. Both the X-ray energy utilization efficiency and the light intensity of the X-ray beam are lowered distinctly while the distance of the focal length is increased for high spatial resolution and high sensitivity. Furthermore, the utilization efficiency is even lowered for improving the tube current to maintain the light intensity. The theoretical analysis and the experimental results show that the sensitivity, spatial resolution and X-ray energy utilization efficiency should be synthetically considered in an optimized X-ray imaging system. [Copyright &y& Elsevier]

Biodegradable magnesium alloy stents (MAS) are a promising solution for long-term adverse events caused by interactions between vessels and permanent stent platforms of drug eluting stents. However, the existing MAS showed severe lumen loss after a few months: too short degradation time may be the main reason for this drawback. In this study, a new design concept of MAS was proposed and a shape optimization method with finite element analysis was applied on two-dimensional (2D) stent models considering four different magnesium alloys: AZ80, AZ31, ZM21, and WE43. A morphing procedure was utilized to facilitate the optimization. Two experiments were carried out for a preliminary validation of the 2D models with good results. The optimized designs were compared to an existing MAS by means of three-dimensional finite element analysis. The results showed that the final optimized design with alloy WE43, compared to the existing MAS, has an increased strut width by approximately 48%, improved safety properties (decreased the maximum principal stress after recoil with tissue by 29%, and decreased the maximum principal strain during expansion by 14%) and improved scaffolding ability (increased by 24%). Accordingly, the degradation time can be expected to extend. The used methodology provides a convenient and practical way to develop novel MAS designs. [ABSTRACT FROM AUTHOR]

The post invention system is an outstanding design that the optimization concerning the man's intellectual resources and a unit's material resources can be realized in terms of the Patent Law . Currently, the proper scope and the distribution of the vested interests of the post invention system must be optimized under the guidance of encouraging invention and realizing the balance of interests so as to deal with a pressure actively which is the result of globalization and the internationalization of the protection of the intellectual property rights, and to maintain the country's economic growth and the expansion of domestic demand on condition that the previous post invention system can be broken down in terms of concept and technology. [ABSTRACT FROM AUTHOR]

A mathematical model has been established for the research on scissor elevator for ship passenger stairs. The kinematical and kinetic simulation analyses were carried out with MATLAB/Simulink. The relative kinetic relation between hydraulic cylinder and other parts, as well as its rules of change has been found. A 3-D model of ship scissor elevator was established with Pro/E. The design of the mechanism was optimized in Pro/MECHANICA based on the findings from simulation analysis. Practice has proved that the design is scientific and reasonable and could serve as the theoretical guidance and reference for the design of scissor mechanism of other uses. [ABSTRACT FROM AUTHOR]

Multi-stage Phase II trials are often employed in practice but may not be the best approach when the endpoint of interest is not obtained soon after enrollment and/or when a control arm is desired. We present a new design in which sample size determination includes a control arm and allows for the estimation of response for each treatment as well as estimation of the difference in the response rates. We evaluate this design under varying allocation schemes to treatment arms and response rates for each treatment. [ABSTRACT FROM AUTHOR]

The finite element analysis (FEA) software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face structure with non-uniform interference. Considering the symmetry of the die, a half gear tooth model of the two-ring assembled die with 2.5 GPa inner pressure was constructed. Four paths were defined to investigate the stress state at the bottom corner of the die where stress concentration was serious. FEA results show that the change of parting face from non-plane to plane can greatly reduce the stress at the teeth tips of the die so that the tip fracture is avoided. The interference structure of the die is the most important influencing factor for the stress concentration at the bottom corner. When non-uniform interference is adopted the first principal stress at the corner on the defined paths of the die is much lower than that with uniform interference. The bottom hole radius is another important influencing factor for the corner stress concentration. The first principal stress at the corner of the plane parting face die with non-uniform interference is reduced from 2.3 to 1.9 GPa when the hole radius increases from 12.5 to 16.0 mm. The optimization of the die structure increases the life of the die from 100 to 6 000 hits. [ABSTRACT FROM AUTHOR]

The present work presents an approach for the optimized design of small gas turbine combustors, that integrates a 0-D code, CFD analyses and an advanced game theory multi-objective optimization algorithm. The output of the 0-D code is a baseline design of the combustor, given the required fuel characteristics, the basic geometry (tubular or annular) and the combustion concept (i.e. lean premixed primary zone or diffusive processes). For the optimization of the baseline design a simplified parametric CAD/mesher model is then defined and submitted to a CFD code. Free parameters of the optimization process are position and size of the liner hole arrays, their total area and the shape of the exit duct, while different objectives are the minimization of NOx emissions, pressure losses and combustor exit Pattern Factor. A 3D simulation of the optimized geometry completes the design procedure. As a first demonstrative example, the integrated design process was applied to a tubular combustion chamber with a lean premixed primary zone for a recuperative methane-fuelled small gas turbine of the 100 kW class. [ABSTRACT FROM AUTHOR]

Auxetic materials exhibit interesting deformation characteristics and excellent mechanical properties. A novel combined tubular structure with tunable stiffness is proposed in this work, aiming to improve the bearing capacity and stability by length design of the central column. Specimens were fabricated via 3D printing technique. Experimental test was performed to study their mechanical property and deformation characteristics under uniaxial compression. The validity of the finite element model was proved by comparing the experimental result with simulation prediction. The compression process and stress-strain curve of the tubular structure with tunable stiffness exhibited four distinct stages (elastic, stiffness change, densification and buckling). Subsequently, a parametrical analysis was conducted to investigate the influences of the central connecting column on the stress-strain response, Poisson's ratio and stability of the structure. By properly choosing the length of the central connecting column, the tubular structure could possess tunable stiffness, higher stability and compressive capacity. Furthermore, this design concept could be of benefit to the development of adaptive structures, smart devices and applications for civil engineering and protective engineering. • The auxetic tubular structure exhibits tunable stiffness and improved mechanical properties. • The stiffness could be tuned artificially through the design of central connecting column. • The influences of the connecting column were explored via parametric analysis. • The stiffness change point ε c t and densification point w ε d t ere proposed via geometric derivation. [ABSTRACT FROM AUTHOR]

• A novel method for designing an eco-friendly UHPC is presented. • A DOD model for multi-object optimization of UHPC is built. • A new UHPC efficiently incorporating steel slag is developed. • The newly developed UHPC exhibits admirable ecological value. This paper addresses an innovative method for the development of eco-friendly ultra-high performance concrete (UHPC), towards efficient steel slag application and synergetic optimization of multi-objective. Specifically, a D-optimal design (DOD) based regression model for property prediction with high goodness of fit (R2 > 0.9) is established. Then, a new UHPC is designed by a numerical optimization method based on the established DOD model. Furthermore, to verify the merit of the designed UHPC, some important properties of the UHPC samples are evaluated. The obtained results reveal that the addition of steel slag powder (SSP) contributes to the improvement of UHPC workability, and the highest slump flow is 268 mm. In addition, the increase of SSP content is detrimental to the early compressive strength, but does not affect the later strength of UHPC (130 ± 2 MPa). Besides, the chloride penetration resistance of UHPC will decrease with the incorporation of SSP, but its anti-chloride permeability is still lower than ordinary concrete. Conclusively, it is demonstrated that the use of this statistical design method could not only benefit environmental protection but also produce a new green UHPC with excellent properties. [ABSTRACT FROM AUTHOR]

The construction system of roller compacted concrete (RCC) dam is running according to a series of connected procedures which are highly impacted and interacted consisting with the resource level. Therefore, a dynamic simulation model of the construction system for RCC dam is presented. With this model, the design of concrete production system is placed in the whole system and tested with related dynamic impactions and interactions under complicated boundaries. Moreover, if several simulation experiments were conducted, plenty of detailed information throughout the construction duration is obtained. Consequently, the optimal one should be chosen on the basis of actual requirement and situation. [ABSTRACT FROM AUTHOR]

An entire set of silicon-based microtechnologies is developed for a high-performance H2/air self-breathing microproton-exchange-membrane fuel-cell (µPEMFC) pack. For improving the performance of the silicon-based µPEMFC, microflow-fields together with the electrodes at the cathode and the anode are optimally designed. For simplifying the microfabrication, a bulk-micromachining process is developed for fabricating both the cathode and the anode. Besides that the optimally designed flow-fields and electrodes are accurate fabricated, both the cathodes and the anodes can be fabricated in a same wafer with identical process. Optimized packaging conditions, such as the compression ratio and the current-collecting layer for the membrane electrode assembly (MEA), are experimentally obtained for both high fuel-cell performance and reliable silicon micropackaging. Attributed to the optimized design and the precise microfabrication, the peak power-density of the self-breathing µPEMFC is measured as high as 141.0-147.2 mW/cm-2. For adapting the output voltage to handheld electronic systems, a thin-pad planar configuration is designed for the µPEMFC pack that consists of six single cells connected in series. The planar-configured self-breathing µLPEMFC pack is micropackaged on a silicon-micromachined base-chip, with the specific power as high as 271 mW/cm³ measured. Experimental results demonstrate that the fuel cells can reliably work under normal environmental temperature and humidity. 1200-h continuing power supply of the µLPEMFC pack is performed, resulting in stable output of about 3 V. [ABSTRACT FROM AUTHOR]

We present an optimized design and detailed simulation of an all-silicon optical modulator based on a silicon waveguide phase shifter containing a metal-oxide-semiconductor (MOS) capacitor. Based on a fully vectorial Maxwell mode solver, we analyze the modal characteristics of the silicon waveguide. We show that shrinking the waveguide size and reducing gate oxide thickness significantly enhances the phase modulation efficiency because of the optical field enhancement in the voltage induced charge layers of the MOS capacitor, which, in turn, induce refractive index modulation in silicon due to free carrier dispersion effects. We also analyze the device speed by transient semiconductor device modeling. As both optical absorption and modulation bandwidth increase with increasing doping concentration, we show that, with a nonuniform doping profile in the waveguide, balance between the device operation speed and optical loss can be realized. Our simulation suggests that a TE-polarized optical phase modulator with a bandwidth of 10 GHz and an on-chip optical loss less than 2 dB is achievable in silicon. [ABSTRACT FROM PUBLISHER]

R&D achievements of a field-running all optical network were summarized. Optimized design scheme of optical add-drop multiplexing (OADM) and optical cross connect (OXC) were also presented. Network control & management (NC&M) issues including the design and implementation were studied. Various network performance metrics were evaluated. The performance test results as well as the fact of good running of the multi-media services show that all-optical network becomes one kind of ideal transport technologies for metropolitan backbone networks. [ABSTRACT FROM AUTHOR]

Alpha particles incident on CMOS integrated circuits deposit charges on circuit nodes resulting in single-event transients (SETs). These transient errors propagate through the circuit and reach a latch where they may get latched under proper conditions. This paper presents circuit design techniques to remove the effects of such SET pulses from the circuit. An optimized design is developed whose area, power, and speed performance is superior to other design methods for SET mitigation. Simulation results showing SET pulse elimination are presented. [ABSTRACT FROM PUBLISHER]

Simulation optimization aims at determining the best values of input parameters, given an output criterion. We address here the much more complex case where design options have to be chosen, which can themselves necessitate choices about other sub-options, as well as numerical parameters. This so-called configuration problem is addressed using simulation associated with a distributed evolutionary algorithm, and is illustrated through an example. This approach allows a large variety of new types of problems to be solved, such as design of complex dynamic systems. In the light of these results, the limits in the optimized configuration of systems are shown to be now determined by the modeling and simulation tools and concepts. In this respect, a possible research direction, based on so-called functional simulation, is discussed and some research perspectives are introduced. [Copyright &y& Elsevier]