Exact boundary integral transformation of the thermoelastic domain integral in BEM for general 2D anisotropic elasticity

In the direct formulation of the boundary element method, body-force and thermal loads manifest themselves as additional volume integral terms in the boundary integral equation. The exact transformation of the volume integral associated with body-force loading into surface ones for two-dimensional elastostatics in general anisotropy, has only very recently been achieved. This paper extends the work to treat two-dimensional thermoelastic problems which, unlike in isotropic elasticity, pose additional complications in the formulation. The success of the exact volume-to-surface integral transformation and its implementation is illustrated with three examples. The present study restores the application of BEM to two-dimensional anisotropic elastostatics as a truly boundary solution technique even when thermal effects are involved.     

BEM Analysis of 3D Heat Conductionin 3D Thin Anisotropic Media

In this paper, the boundary integrals for treating 3D field problems are fully regularized for planar elements by the technique of integration by parts (IBP). As has been well documented in open literatures, these integrals appear to be strongly singular and hyper-singular for the associated fundamental solutions. In the past, the IBP approach has only been applied to regularize the integrals for 2D problems. The present work shows that the IBP can also be further extended to treat 3D problems, where two variables of the local coordinates are involved. The presented formulations are fully explicit and also, most importantly, very straightforward for implementation in program codes. To demonstrate their validity and our implementation, a few example cases of 3D anisotropic heat conduction are investigated by the boundary element method and the calculated results are verified using analyses by ANSYS.     

Analysis for Thermal Conductance Effect on the Interfacial Thermal Stresses of Anisotropic Composites

The present work applies the regularized boundary integral equations that are newly developed to treat the thermoelastic field in thin anisotropic media. For the anisotropic thermal field, a direct domain mapping technique is applied with a unique interface condition that considers the heat conductance relation. By incorporating the heat conductance effect, the paper investigates how interfacial thermal stresses between generally anisotropic materials vary with the heat conductance coefficient. Accounting for the thermal conductance effect, the paper presents the complete algorithm for computing the thermal as well as the subsequent elastic fields on interfaces between dissimilarly adjoined anisotropic composites.     

State-of-Charge Estimation for Electric Scooters by Using Learning Mechanisms

Because of its nonlinear discharge characteristics, the residual electric energy of a battery remains an open problem. As a result, the reliability of electric scooters or electric vehicles is lacking. To alleviate this problem and enhance the capabilities of present electric scooters or vehicles, we propose a state-of-charge learning system that can provide more accurate information about the state-of-charge or residual capacity when a battery discharges under dynamic conditions. The proposed system is implemented by learning controllers, fuzzy neural networks, and cerebellar-model-articulation-controller networks, which can estimate and predict nonlinear characteristics of the energy consumption of a battery. With this learning system, not only could it give an estimate of how much residual battery power is available, but it also could provide users with more useful information such as an estimated traveling distance at a given speed and the maximum allowable speed to guarantee safe arrival at the destination     

BEM Analysis of Interior Thermal Stresses Near the Boundary of Anisotropic Materials

In engineering applications, residual thermal stresses inside materials may lead to structural warp. Thus, accurate analysis of thermal stresses inside materials is of great importance for the assessment of structural integrity and performance. Emerging as an effective alternative of numerical tools, the boundary element method is well known for its notion that only the boundary needs to be discretised. However, the stress computations for interior points near the boundary will have numerical difficulty stemming from nearly singular integrals. This article presents a novel boundary integral equation that is fully regularized for computation of thermal stresses inside anisotropic materials. The veracity and applicability of the formulations derived are demonstrated by numerical examples at the end.     

Heat conduction of thin anisotropic composites subjected to convection

Composites made of thin layers can be found in many engineering applications. One of the most crucial issues for the design of such applications is the heat convection required to ensure the safety of the device subjected to the most severe temperature under operation. The finite element method, although popular for engineering analysis, is not generally an ideal numerical tool for analysis of ultra-thin media. As an effective alternative, the boundary element method may be applied for the analysis. This article deals with the heat convection of thin anisotropic layers by the boundary element method. At the end, some benchmark examples are investigated as illustrations of the veracity and applicability of the scheme.     

An inductively powered implantable blood flow sensor microsystem for vascular grafts

Monitoring blood flow rate inside prosthetic vascular grafts enables an early detection of the graft degradation, followed by the timely intervention and prevention of the graft failure. This paper presents an inductively powered implantable blood flow sensor microsystem with bidirectional telemetry. The microsystem integrates silicon nanowire (SiNW) sensors with tunable piezoresistivity, an ultralow-power application-specific integrated circuit (ASIC), and two miniature coils that are coupled with a larger coil in an external monitoring unit to form a passive wireless link. Operating at 13.56-MHz carrier frequency, the implantable microsystem receives power and command from the external unit and backscatters digitized sensor readout through the coupling coils. The ASIC fabricated in 0.18-μm CMOS process occupies an active area of 1.5 × 1.78?mm (2) and consumes 21.6 μW only. The sensors based on the SiNW and diaphragm structure provide a gauge factor higher than 300 when a small negative tuning voltage (-0.5-0?V) is applied. The measured performance of the pressure sensor and ASIC has demonstrated 0.176 mmHg/√Hz sensing resolution.     

GABA function in mood disorders: an update and critical review

Over the past twenty years, several lines of evidence from preclinical and clinical studies has accumulated suggesting that a GABA deficit may be involved in mood disorders, particularly in depression, and that increasing GABAergic neurotransmission may exert an antidepressant effect and perhaps a mood stabilizing effect. Given that GABA has an inhibitory effect on biogenic amine neurotransmitters such as norepinephrine and serotonin and this inhibition may be involved in local circuits and interneurons, it has been suggested that the hypothesis of a GABA deficit in mood disorders does not compete with but complements the well-established hypotheses of alterations in noradrenergic and serotonergic function in mood disorders. In this paper, we systematically reviewed the results from preclinical and clinical studies of GABA function in the pathophysiology of mood disorders and in the mechanism of action of mood stabilizers, antidepressants and electroconvulsive therapy. We also discussed the unifying theory of the neurochemistry of mood disorders, which integrates the GABA hypothesis into the biogenic amine hypotheses, and indicated future directions for research.     

Parametric analysis of proton exchange membrane fuel cell performance by using the Taguchi method and a neural network

This study proposes a novel parameter optimization method, capable of integrating the neural network and the Taguchi method for parametric analysis of proton exchange membrane fuel cell (PEMFC) performance. Numerous parameters affecting the PEMFC performance are analyzed, such as fuel cell operating temperatures, cathode and anode humidification temperatures, operating pressures, and reactant flow rate. In the traditional design of experiments, the Taguchi method has been popularly utilized in engineering. However, the parameter levels selected to form the orthogonal array in the Taguchi method are discrete, preventing the estimation of the real optimum. This study used the Taguchi method to acquire the primary optimums of the operating parameters in the PEMFC. Each row in the orthogonal array together with its relative responses was used to establish a set of training patterns (input/target pair) to the neural network. The neural network can then construct relationships between the control factors and responses in the PEMFC. The actual optimums of the operating parameters in the PEMFC were obtained by the trained neural network. Experimental results are presented for identifying the proposed approach, which is useful in improving performance for PEMFC and developing electrical system on advanced vehicles and ships.     

BEM treatment of two-dimensional anisotropic field problems by direct domain mapping

Using the method of characteristics, a steady-state anisotropic field problem can be reduced to one governed by Laplace's equation in a mapped plane. No rotation of axes is involved in the process, and the coordinate transformation equations are given in this paper. The advantage of this approach is that the anisotropic problem can be easily solved with any of the readily available boundary element method (BEM) programs for ‘isotropic’ potential theory, albeit on a distorted domain. Two numerical examples are presented to illustrate the scheme.