Reduction In Dissipation Research Articles

Aggressive Approximation of the SoftMax Function for Power-Efficient Hardware Implementations

Neural Network models most often exploit the SoftMax function in the classification stage for computing probabilities through exponentiation and division operations. To reduce the complexity and the energy consumption of such stage, several hardware-friendly approximation strategies have been disclosed in the recent past. This brief evaluates the effects of an aggressive approximation of the SoftMax layer on both classification accuracy and hardware characteristics. Experimental results demonstrate that the proposed circuit, when implemented in a 28 nm FDSOI technology, saves ~65% of silicon area with respect to competitors, dissipating less than 1 pJ. FPGA implementation results confirm a massive energy dissipation reduction with respect to the conventional baseline architecture, without introducing penalties in the Top-1 accuracy.

Performance Comparison of the Conventional CMOS and MTCMOS Digital Circuits and Their Simulation

This paper focuses on the design of the conventional CMOS digital circuits and the Multi-Threshold CMOS (MTCMOS) digital circuits, which perform the specific Boolean logic function, as well as the comparison between these designing techniques by their functionality and power consummation (dissipation). The leakage of currents in integrated circuits based on CMOS logic becomes quite significant when the complementary MOS transistors are the small-device geometries (small dimensions), and this effect imposes alternative techniques that enable the designing of CMOS digital circuits with low-power dissipation, even in standby mode. One of these techniques is the design of the CMOS digital circuits with multi-threshold voltage (MTCMOS), which enables the reduction of the leakage power dissipation, as a part of the overall power dissipation in CMOS logic. Two CMOS digital circuits are designed (2-input XNOR CMOS gate and the other one is the CMOS gate that performs a complex Boolean function) based on conventional CMOS technique and multi-threshold voltage CMOS technique, and their functionality and calculation of the average overall power dissipation are tested using the Computer-Aided Design (CAD). The methodology used to achieve low power dissipation in CMOS digital circuits (MTCMOS) will be an efficient method for reducing the overall dissipation, while the high speed performance will be maintained.

Lemon-Derived Extracellular Vesicles Nanodrugs Enable to Efficiently Overcome Cancer Multidrug Resistance by Endocytosis-Triggered Energy Dissipation and Energy Production Reduction.

Multidrug resistance remains a great challenge for cancer chemotherapy. Herein, a biomimetic drug delivery system based on lemon‐derived extracellular vesicles (EVs) nanodrugs (marked with heparin‐cRGD‐EVs‐doxorubicin (HRED)) is demonstrated, achieving highly efficient overcoming cancer multidrug resistance. The HRED is fabricated by modifying functional heparin‐cRGD (HR) onto the surface of EVs and then by loading with doxorubicin (DOX). The obtained HRED enable to effectively enter DOX‐resistant cancer cells by caveolin‐mediated endocytosis (main), macropinocytosis (secondary), and clathrin‐mediated endocytosis (last), exhibiting excellent cellular uptake capacity. The diversified endocytosis capacity of HRED can efficiently dissipate intracellular energy and meanwhile trigger downstream production reduction of adenosine triphosphate (ATP), leading to a significant reduction of drug efflux. Consequently, they show excellent anti‐proliferation capacities to DOX‐resistant ovarian cancer, ensuring the efficiently overcoming ovarian cancer multidrug resistance in vivo. The authors believe this strategy provides a new strategy by endocytosis triggered‐energy dissipation and ATP production reduction to design drug delivery system for overcoming cancer multidrug resistance.

Comparative analysis of STT and SOT based MRAMs for last level caches

In recent years, magnetic RAMs have stimulated considerable research interest due to its high area-density and low leakage-power with comparable speed that makes it a strong contender for possible replacement of conventional RAMs. However, the operational speed of MRAM is relatively lower than the SRAMs. Advanced switching mechanism such as Spin Transfer Torque (STT), Voltage-Controlled Magnetic Anisotropy (VCMA), Magneto Electric (ME) effect, and Spin-Orbit Torque (SOT) has been introduced to further improve the speed of operation. This paper explores the comparative analysis of STT and SOT-based MRAMs for the application of Large Last-Level Caches (L3Cs). It will give an insight into the MRAM from device to architectural level, in-aspect of performance parameters such as read-write energy consumption, leakage power, chip-area and read-write latency. This research work is carried out through a benchmarked simulation framework, starting from device to architectural level. At the cell level, it is observed that STT-MRAM takes 50% less area with 74% reduction in leakage power dissipation as compared to SOT-MRAM. However, the SOT-MRAMs is 4× faster than the STT-MRAM. At the architectural level, SOT-MRAM outperforms STT-MRAM in terms of read/ write energy and latency at the cost of marginal chip-area and leakage-power. Overall, in comparison to its conventional counterpart (SRAMs), SOT MRAMs are proved to be a superior candidate at a large size of LLCs in all aspects.

Improving transcatheter aortic valve interventional predictability via fluid-structure interaction modelling using patient-specific anatomy.

Transcatheter aortic valve replacement (TAVR) is now a standard treatment for high-surgical-risk patients with severe aortic valve stenosis. TAVR is being explored for broader indications including degenerated bioprosthetic valves, bicuspid valves and for aortic valve (AV) insufficiency. It is, however, challenging to predict whether the chosen valve size, design or its orientation would produce the most-optimal haemodynamics in the patient. Here, we present a novel patient-specific evaluation framework to realistically predict the patient's AV performance with a high-fidelity fluid–structure interaction analysis that included the patient's left ventricle and ascending aorta (AAo). We retrospectively evaluated the pre- and post-TAVR dynamics of a patient who underwent a 23 mm TAVR and evaluated against the patient's virtually de-calcified AV serving as a hypothetical benchmark. Our model predictions were consistent with clinical data. Stenosed AV produced a turbulent flow during peak-systole, while aortic flow with TAVR and de-calcified AV were both in the laminar-to-turbulent transitional regime with an estimated fivefold reduction in viscous dissipation. For TAVR, dissipation was highest during early systole when valve deformation was the greatest, suggesting that an efficient valve opening may reduce energy loss. Our study demonstrates that such patient-specific modelling frameworks can be used to improve predictability and in the planning of AV interventions.

Experimental assessment of the behavior of expanded glass lightweight reinforced concrete walls

Structural lightweight concrete (LWC) can significantly reduce the dead loads of reinforced concrete (RC) structures and therefore the associated seismic forces. A new LWC was made using expanded glass as lightweight aggregate (LWA), which is comparatively much lighter than conventional LWAs, and might lead to different performance in lightweight RC elements. An experimental study was conducted to evaluate the structural behavior of expanded glass LWC RC walls. Two types of RC walls were built and tested under cyclic displacement protocol: slender confined and squat unconfined walls. For each type of wall, four specimens were considered: two with LWCs with fc′ of 30 and 40 MPa (i.e., L30 and L40) and densities of 1200 and 1700 kg/m3, respectively; and two with normal weight concretes (NWC) with the same specified strengths acting as control specimens (i.e., N30 and N40) and a density of about 2400 kg/m3. These walls were analyzed in terms of yield drifts and strengths, maximum drifts and strengths, ductility and energy dissipation. Results show that slender confined walls made with L30 mixture showed reductions in ductility and energy dissipation of about 56 and 34%, respectively when compared to N30 specimens. Meanwhile, L40 specimens showed the same tendency, but with smaller reductions compared to N40 of about 36% of ductility and 10% of energy dissipation. In squat unconfined walls, a significant reduction of strength was observed for both types of LWCs, although a bigger difference was observed in L30 concrete. Overall, expanded glass LWC showed promising structural behavior, especially L40 mixture, which presented relatively small differences compared to its NWC counterpart and had only 70% of its unit weight.

A Novel Module-Sign Low-Power Implementation for the DLMS Adaptive Filter With Low Steady-State Error

In this paper, a novel implementation is proposed for the Delayed LMS (DLMS) filter, able to reduce the power dissipation while preserving regime performances. The approach relies on the observation that the error signal is small in magnitude and oscillates around zero when the circuit is close to the convergence point. Therefore, the most significant bits of the error signal continuously toggle from positive to negative values causing high switching activity in the multipliers of the feedback section. This paper proposes to employ a sign-modulus representation of the error signal, to substantially reduce the switching activity of the feedback path of the filter. Additional approximation techniques are also devised to further reduce power dissipation. Comparisons with the state-of-the-art show that the proposed filter is the only one able to approach the MSE of the exact implementation with a remarkable reduction of power dissipation. A test-chip in TSMC 28nm CMOS technology has been realized to experimentally verify the validity of our technique. The experimental results show the possibility of saving up to 45.4% of power consumption with respect to the exact implementation of the filter.

A Practical Energy/Power Reduction Approach for Parallel Decimal Multiplier

Decimal computation is highly demanded in many human-centric applications such as banking, accounting, tax calculation, and currency conversion. Hence the design and implementation of radix-10 arithmetic units attract the attention of many researchers. Among the basic decimal arithmetic operations, multiplication is not only a frequent operation but also has high complexity and considerable power consumption. Therefore, this paper concentrates on this issue and studies a general design methodology that reduces power/energy consumption via localizing switching activity without compromising target performance. This method decomposes a digit multiplier into smaller ones, like Karatsuba’s algorithm, while the multiplicand and the multiplier can be partitioned into different sizes. We take advantage of various size partitions in two types of symmetric and asymmetric, which final designs provide specific characteristics. All designs were implemented using VHDL and synthesized in the Design-Compiler toolbox with TSMC 130 nm Technology file. The results are significant; in respect to the original design, by a random test vector, 25% power reduction is achieved with no effect on latency and a negligible area penalty. Moreover, the experimental results indicate a potential for considerable reduction of power dissipation based on statistical properties of possible input data.

Discretization and Model Reduction Error Estimation of Interconnected Dynamical Systems

In this paper a novel approach for estimating both discretization and model order reduction error is presented. Discretization is carried out using finite element method. Finite element models are converted to linear time-invariant state space models. Using the generalized square root balanced truncation method a series of reduced models are obtained. It is shown that for special class of passive and dissipative dynamical systems upper a-posteriori reduction error bound can be modeled less conservatively. Estimation of both discretization and model reduction error is further refined using v-gap metric. Quality of the obtained reduced order model is verified in the frequency domain. The proposed error estimation approach is demonstrated on a numerical example.

Geometric parameters optimization of low resistance T-junction with guide vanes in HVAC system

In recent years, with the increasing energy consumption and carbon emissions, people are paying more and more attention to related measures for energy conservation and emission reduction. As an important conveying component of the HVAC system, the pipe network system plays the function of distributing the fluid medium. However, a large part of the resistance loss is often generated during this transportation process, and the local pressure loss caused by local resistance components (e.g., T-junction) accounts for a large part of the total pressure drop. In this work, the influence of different guide vane positions on the resistance of the T-junction is analyzed. The internal flow field distribution and resistance characteristics of the T-junction are explored by numerical calculation method. The total energy dissipation and resistance reduction rate of the traditional T-junction and the novel T-junction with a guide vane are compared under different flow ratios. The resistance reduction rate of the optimized T-junction with a guide vane is 21.5%. The insertion of guide vanes can reduce the flow resistance and total energy loss of T-junction.

Multi-Channel, Actively Shielded, Power Efficient MRI Z-Gradient Cylindrical Coil Design Using Target-Field Method

Gradient coils are essential for MRI where fast and large electrical current pulses are typically applied to conventional, single-channel gradient coils, particularly for high-performance gradient applications. However, these pulses result in significant power losses and heating of the coil. We investigate the design of power-efficient multi-channel Z-gradient coils operating in the conventional mode comparing them to conventional single-channel coils designed using similar dimensions and alike DC performance characteristics. The power-efficiencies of thirteen different two-channel configurations having various section lengths for two different dimensions are analyzed. The current density of each section is approximated by Fourier series expansion where a linear equation relating the desired target field and current density is formulated and then solved. A stream function is derived from the obtained current density and then used to extract the final winding patterns of each section using a particular track width and a specific number of turns. The design process involves optimizing the current driving each channel, the distribution of coil windings, and the section size. Similarly, the performance of three-channel coils is also investigated. Results show that a power dissipation reduction of 17-28% and ~23% can be achieved using two- and three-channel coils, respectively. Moreover, we showed that multi-channel coils may have a slightly better shielding efficiency compared to conventional coils. A new methodology for designing two- and three-channel coils is presented where an advantage in terms of power efficiency can be gained depending on design parameters, coil’s dimensions, number of turns, and other metrics.

RETRACTED: Design of 8-bit Dynamic CMOS Priority Resolvers based on Active- High and Active-Low Logic

A couple of new dynamic CMOS based designs of an 8-bit priority resolver corresponding to activehigh and active-low logic are presented in this paper. The proposed designs result from modifications to an 8- bit priority resolver designed by Huang and Chang [15], which pertains to active-high logic. Compared to Huang and Chang’s original 8-bit CMOS priority resolver, the modified designs achieve 4× mean reduction in power dissipation, and report average improvement in the power-delay product by 43%. The simulation results were obtained using Tanner tools (TSPICE), and correspond to a 0.25μm CMOS process technology.

The Influence of Shell Permeability on Stability of Upstream Slope during Rapid Drawdown – Khassa Chai Earth Dam as a Case Study

Several factors affect the stability of earth dam during sudden drawdowns such as permeability and mechanical properties of soil, upstream side slope, drawdown ratio, and drawdown rate. This paper investigates the influence of shell permeability on earth dam upstream slope stability and its role in the change of pore water pressure at different locations of the embankment during the sudden drawdown, using different limit equilibrium methods. To accomplish the objective of this study, (Geo Studio 2012 Software) as one of the powerful geotechnical programs was used for the modeling and numerical analysis. The study shows that decreasing in the shell permeability resulted in the reduction of pore water pressure dissipation and variation of shell hydraulic conductivity plays a vital role in the overall stability of the upstream slope under rapid drawdown conditions.

Effects of boron nitride and carbon nanotube on damping properties, thermal conductivity and compression stress relaxation behavior of BIIR

AbstractAs highly integrated electronic components and devices are used under high electrical power and mechanical vibration, the thermal conductivity, damping properties, and compression stress relaxation of protection materials have become critical factors which affect the long‐term durability and reliability of the materials. Damping rubbers are widely used, but their thermal conductivity and compression stress relaxation are rarely studied. Herein, the effects of boron nitride (BN) and carbon nanotube on the damping properties, thermal conductivity, and compression stress relaxation behavior of brominated butyl rubber (BIIR) are investigated. BN increases the damping factor of BIIR and widens its effective damping temperature range. The maximum damping factor of BIIR composite with 12.3 wt% BN is 0.95, and the effective damping temperature range is −41 to 60°C. Moreover, the thermal conductivity of BIIR with 12.3 wt% BN is 0.46, much higher than that of BIIR. With increasing BN content, the thermal conductivity of BIIR/BN composites increases gradually, while their stress relaxation rate decreases. Carbon nanotube can further increase the thermal conductivity of BIIR/BN composites. BIIR/BN composites with high damping properties and thermal conductivity have a great application potential in the heat dissipation and vibration reduction of electronic devices.

Electrical Efficiency Increase in CPVT Collectors by Spectral Splitting

Concentrating photovoltaic-thermal (CPVT) collectors have to face the challenge of contrary temperature requirements in the single receiver parts. The PV cells require low temperatures to achieve high efficiency, whereas the thermal part should generate high temperatures for providing industrial heat. The approach of “Spectral Splitting” can offer a solution for compact CPVT receivers; however, a clear quantification of the expected conversion efficiency is difficult. Therefore, this paper describes a modelling methodology for obtaining electrical and thermal performance parameters for a Spectral Splitting configuration using semiconductor-doped glass combined with appropriate heat transfer fluid. The PV technologies c-Si, CIGS and CdTe are considered. The presented model yields distinct results for maximising the electrical efficiency, calculates the reduction in waste heat dissipation within the cells and assesses the impacts of concentration factor and cell temperature. An optimised configuration could be found with CIGS cells, impinged by a selected wavelength spectrum between 868 nm and 1100 nm, where the theoretical efficiency reaches 42.9%. The waste heat dissipation within the cells is reduced by 84.9%, compared to a full-spectrum operation. The depicted CPVT receiver design using bendable thin-film PV cells will be realised as a prototype in a subsequent project phase.

Viscous energy dissipation reduction by optimization of multiple shapes

AbstractShape optimization has been an active field of research for the past decades and is used especially in engineering. On this poster, we consider a shape optimization model with multiple shapes, i.e., we consider more than one shape to be optimized. We assume that the optimization variable is a set Γ = (Γ1,…, ΓN) of non‐intersecting shapes contained in a bounded domain D ⊂ ℝd. We note that D depends on Γ, i.e., D = D(Γ). On this poster, a shape optimization of a two‐dimensional fluid‐mechanical problem is considered. We minimize the viscous energy dissipation in the fluid domain D, more precisely urn:x-wiley:16177061:media:PAMM202100261:pamm202100261-math-0001 subject to the equations describing Stokes flow urn:x-wiley:16177061:media:PAMM202100261:pamm202100261-math-0002 urn:x-wiley:16177061:media:PAMM202100261:pamm202100261-math-0003 with appropriate boundary conditions, where y ∈ ℝ2 describes the fluid velocity, p ∈ ℝ the pressure, and f ∈ ℝ2 a given source term. In order to solve the minimization problem, we use an optimization approach based on the Steklov‐Poincaré metric, where the so‐called weak form of the shape derivative can be used. The algorithm and implementation details are presented, and numerical results are discussed for the optimization of multiple shapes in the fluid domain.

A temperature dependent constitutive model for functional fatigue in shape memory alloys

Functional fatigue is a vital aspect when considering the design of components made with shape memory alloys, since it can affect their short- and long-term behavior. With this in mind, a constitutive model considering the functional fatigue in shape memory alloys is developed. The functional fatigue is based on the residual strain, residual stress, residual martensite and a defect volume fraction, which are assumed to all evolve in a similar manner. The evolution is prescribed based on a saturation differential equation which is exponentially dependent on temperature. The residual martensite and defect volume fraction are defined to influence the development of hardening through a hardening energy term and the reduction in dissipation with an appropriate limit function. The model is validated by simulating several experiments of cyclic isothermal and isobaric tests. A fit and prediction is also offered for a set of complex thermomechanical loading paths. The results demonstrate the strong applicability of the model to capture the degradation of the transformation response associated with cyclic loads, even when different temperatures and loads are applied. Moreover, the results point out areas of improvement, such as the use of a logarithmic evolution for the saturation of the internal variables.

Probabilistic Value-Deviation-Bounded Source-Dependent Bit-Level Channel Adaptation for Approximate Communication

Computing systems that can tolerate effects of errors in their communicated data values can trade this tolerance for improved resource efficiency. Many important applications of computing, such as embedded sensor systems, can tolerate errors that are bounded in their distribution of deviation from correctness (distortion). We present a channel adaptation technique which modulates properties of I/O channels typical in embedded sensor systems, to provide a tradeoff between I/O power dissipation and distortion of communicated data. We provide an efficient-to-compute formulation for the distribution of integer distortion accounting for the distribution of transmitted values. Using this formulation we implement our value-deviation-bounded (VDB) channel adaptation. We experimentally quantify the achieved reduction in power dissipation on a hardware prototype integrated with the required programmable channel modulation circuitry. We augment these experimental measurements with an analysis of the distributions of distortions. We show that our probabilistic VDB channel adaptation can provide up to a 2× reduction in I/O power dissipation. When synthesized for a miniature low-power FPGA intended for use in sensor interfaces, a register transfer level implementation of the channel adaptation control logic requires only 106 flip-flops and 224 4-input LUTs for implementing per-bit channel adaptation on serialized streams of 8-bit sensor data.

Comprehensive investigation of various bypass diode associations for killer-SuDoKu PV array under several shading conditions

This paper investigates the electrical behavior of total cross tied (TCT), SuDoKu (SDK) and killer-SDK (KSDK) configurations under several shading conditions. Three different types of bypass diode (BD) arrangements for these PV arrays (PVAs) have been reported and the considered different BD arrangements are without BD (WBD), non-overlapped BD (NBD) and overlapped BD (OBD). Due to the occurrence of shading situations, the investigation of excess current for various BD based PVA configurations has been carried out. In the present work, maximum prospecting values of excess current for PV modules and arrays are also reported. Moreover, comparative analysis between WBD, NBD and OBD based PVA configurations has been presented using P–V and I–V characteristics. Also, investigation has been extended in terms of reduction of excess current, power dissipation, power improvement, energy savings and earnings. The presented results may be used as a suggestion for appropriate BD interconnection for the chosen PVA configurations. Overall, it is reported in this article that the NBD based KSDK PVA configuration is superior to WBD, OBD and NBD based TCT and SDK PVA configurations.

Dissipation Reduction and Information-to-Measurement Conversion in DNA Pulling Experiments with Feedback Protocols

Information-to-energy conversion with feedback measurement stands as one of the most intriguing aspects of the thermodynamics of information in the nanoscale. To date, experiments have focused on feedback protocols for work extraction. Here we address the novel case of dissipation reduction in non-equilibrium systems with feedback. We perform pulling experiments on DNA hairpins with optical tweezers, with a general feedback protocol based on multiple measurements that includes either discrete-time or continuous-time feedback. While feedback can reduce dissipation, it remains unanswered whether it also improves free energy determination (information-to-measurement conversion). We define thermodynamic information {\Upsilon} as the natural logarithm of the feedback efficacy, a quantitative measure of the efficiency of information-to-energy and information-to-measurement conversion in feedback protocols. We find that discrete and continuous-time feedback reduces dissipation by roughly kBT{\Upsilon} without improvement in free energy determination. Remarkably, a feedback strategy (defined as a correlated sequence of feedback protocols) further reduces dissipation, enhancing information-to-measurement efficiency. Our study underlines the role of temporal correlations to develop feedback strategies for efficient information-to-energy conversion in small systems.