mW Of Power Research Articles

A 206.4 dBc/Hz FoMT Class-F23 VCO using nonlinear-capacitance-transforming technique

—In this paper, a class-F23 VCO using nonlinear-capacitance transforming technique to simultaneously achieve low phase noise and a wide tuning range is proposed. The phase noise degradation due to the nonlinearity of the switched capacitor in the class-F23 oscillator is analyzed and quantitatively derived. The phase noise contributed by the nonlinear capacitance can be suppressed by using the proposed nonlinear-capacitance transformation technique. In order to achieve low phase noise over a wide bandwidth, the asymmetric-toggling method is utilized to achieve optimal capacitance ratios across the entire frequency range. Implemented in a 40-nm CMOS process, the proposed oscillator exhibits 41.2 % tuning range from 2.58 GHz to 3.92 GHz while consuming 13.8 mW–14.9 mW power dissipation. The phase noises at 2.58 GHz and 3.92 GHz oscillation frequencies are −136.4 dBc/Hz and −129.6 dBc/Hz at 1-MHz offset. The minimum phase noise is −157.2 dBc/Hz at 10 MHz offset, corresponding to an FoM of 194.1 dBc/Hz and FoMT of 206.4 dBc/Hz.

Energy, Exergy, Exergoeconomic, and Environmental (4E) Analysis of the Existing Gas Turbine Power Plants in BOB - PT. Bumi Siak Pusako Pertamina

The power plants in Indonesia are mostly used to supply energy for the industrial sector, including the upstream oil and gas as well as mining companies. Several companies operating in Riau contribute to the status of the region as the largest oil producer in Indonesia. These companies rely on self-generated electricity for their operations with subsequent impact on the environment. Therefore, this research was conducted to analyze the flow of energy, exergy, exergoeconomic, and environment at the 6 MW power plant operated by BOB - PT Bumi Siak Pusako - Pertamina Hulu. The second law of thermodynamics was used to evaluate energy efficiency as the maximum achievable effort. This was further integrated with economic principles to appraise the useful and wasted costs associated with thermodynamic systems through the concept of exergoeconomics. The results showed that the thermal efficiency of the gas turbine power plant was 42.85% and the exergy efficiency was 33.22% with the largest loss recorded in the combustion chamber to be 3.091 MW in the form of vibration, friction, or expansion of the components. It was also discovered that the exergy efficiency of each component was above 75%, thereby indicating the components of the gas turbine power plant components were in good condition. Moreover, the largest exergy destruction cost was 2349.16 USD/h and the exergy cost was 3,778.05 USD/kWh. The exhaust emission generated by the gas turbine power plant was 0.21 kg/s or equivalent to 0.1425 kg/kWh requiring a forest area of 11.63 ha. The results showed that the analytical method used could be comprehensively developed and applied to other power plants in Indonesia. It could also be used to understand system performance, identify energy losses, optimize energy efficiency, and link economic aspects with energy use.

On the prediction of the induced damage by the start-up sequence of Francis turbines: On operational resilience framework

The number of transient operations in hydraulic machinery connected to power grid, notably start-ups and shut-downs, has observed a substantial increase in recent decades, primarily driven by the global shift towards intermittent renewable energy sources. Simultaneously, advancements in MW power converter technology and its cost-effectiveness have altered the operational paradigms of hydropower plants. These transformations offer novel opportunities for asset management within the industry. This study introduces a new method aimed at forecasting stress during start-up procedures, leveraging steady-state measurements acquired from a reduced scale model of the hydraulic turbine. Through a dedicated modular telemetry measurement system and the integration of strain gauges onto the reduced-scale runner blades, a tool is devised to predict dynamic loads characteristic of these transient operations. Utilizing steady-state measurements and a Voronoi cell tessellation, the transient predicted stress signal is constructed by concatenating the information from each encountered cell, thus providing an estimated projection of the stress likely to occur during the sequence. The proposed methodology demonstrates a robust forecast of the stresses on the runner blades during steady-state and transient operations of Francis turbines. Its immediate value lies in the ability to correctly estimate the lifetime of the runner as well as the possible integration into an optimization framework for stress reduction, thereby potentially extending the operational lifespan of the unit, from the runner structure perspectives.

Quantization-Based Optimization Algorithm for Hardware Implementation of Convolution Neural Networks

Convolutional neural networks (CNNs) have demonstrated remarkable performance in many areas but require significant computation and storage resources. Quantization is an effective method to reduce CNN complexity and implementation. The main research objective is to develop a scalable quantization algorithm for CNN hardware design and model the performance metrics for the purpose of CNN implementation in resource-constrained devices (RCDs) and optimizing layers in deep neural networks (DNNs). The algorithm novelty is based on blending two quantization techniques to perform full model quantization with optimum accuracy, and without additional neurons. The algorithm is applied to a selected CNN model and implemented on an FPGA. Implementing CNN using broad data is not possible due to capacity issues. With the proposed quantization algorithm, we succeeded in implementing the model on the FPGA using 16-, 12-, and 8-bit quantization. Compared to the 16-bit design, the 8-bit design offers a 44% decrease in resource utilization, and achieves power and energy reductions of 41% and 42%, respectively. Models show that trading off one quantization bit yields savings of approximately 5.4K LUTs, 4% logic utilization, 46.9 mW power, and 147 μJ energy. The models were also used to estimate performance metrics for a sample DNN design.

Ultra-low power, high-data rate, fully on-chip radio frequency on-off keying receiver for internet-of-things applications

Despite the enormous potential of energy-efficient receivers for wireless sensor networks, the large power consumption or limited data rate support impedes its extensive applications. Here, we present an energy-efficient, ultra-low power, higher data rate supporting, completely on-chip radio-frequency receiver frontend for on-off keying modulated signals in the 2.4 GHz industrial, scientific, and medical band. This compact-sized receiver is achieved by implementing temperature-resilient oscillator, pseudo-differential mixer, and a wideband detector while avoiding bulky external components such as bulk-acoustic wave resonators, crystal oscillators. Measurement results demonstrate that the proposed on-off keying receiver can decode low power level radio-frequency signals up to 5 Mbps data rate while consuming only 178 µW power. This work also demonstrates support for lower data rates at reduced power. Since the proposed receiver operates in different power modes, it can be integrated in diverse applications including internet-of-things devices and continuously monitoring biomedical/wearable implants.

Introducing and performance evaluation of a novel Multi-Generation process for producing Power, fresh Water, oxygen and nitrogen integrated with liquefied natural gas regasification and carbon dioxide removal process

The objective of this paper is to develop and evaluate a new integrated multigenerational system comprised of cryogenic air separation, hydrate-based desalination, combined cycle and oxyfuel power plants, carbon dioxide amine absorption, and transcritical carbon dioxide power cycle, employing liquefied natural gas cold energy. This integrated multi-generation system, applicable for liquefied natural gas importer terminals with access to seawater, produces approximately 2,533 MW net output power and 1,985 kg/h fresh water. In addition, this integrated multi-generation process produces 16,735,861 kg/h high-purity liquid oxygen (100 mol%), 4,773,633 kg/h liquid nitrogen with 99.71 mol% purity, more than 31,724,465 kg/h high-purity gaseous nitrogen (99.9 mol%), and 90,903,230 kg/h low-purity gaseous nitrogen (83.38 mol%). About 5907.3 MW of produced power is generated by liquefied natural gas expander. The performance of this system is evaluated by energetic methods. The results of energy analysis show the specific energy consumptions of the air separation products are 0.551 kW/kg and 1.93 kW/kg for liquid oxygen and nitrogen, respectively. Moreover, in the hydrate-based desalination subsystem, the specific energy consumption is 0.5 kW/m3 for produced pure water. The combined cycle power plant includes two gas turbines, three steam turbines, and a three-pressure level heat recovery steam generation. The thermal efficiencies of gas turbine cycles (Bryton), steam turbine cycles (Rankine) and combined power cycles are 26.3 %, 29.6 %, and 36.2 %, respectively. The flue gases from power plants enter the carbon dioxide amine absorption subsystem. The separated carbon dioxide is used as a working fluid to produce 372.1 MW power in transcritical carbon dioxide cycle. The results of energy analysis for carbon dioxide amine absorption subsystem show that the specific energy consumption, the ratio of captured carbon dioxide per unit mass of liquefied natural gas and the carbon dioxide removal efficiency are 6.60 kW/kg, 33.91 kg/tone, and 90.06 %, respectively. Approximately 2,905,000 kg/h of liquid carbon dioxide is obtained as the byproduct of this multi-generation process. Additionally, sensitivity analysis is conducted to determine key parameters influencing the main energetic indexes. Finally, the amount of attainable regasified natural gas reaches 257,523 tone/h by applying this multi-generation system with total 86 % energy efficiency.

Flexible and stretchable high performance enzymatic biofuel cells implantable in tube-type artificial blood vessel kit

Enzymatic biofuel cells (EBFCs) are emerged as promising power sources for implantable devices, offering excellent form factor and performance. For these applications, EBFCs require customer tailored structure and more than 10 μW power. In this study, flexible and stretchable EBFCs are suggested, assessing their performance using tube-type artificial blood vessel (TABV) cell kit with sheep blood fuel. To fabricate the EBFCs, buckypaper (BP) is molded to polydimethylsiloxane (PDMS) to fabricate BP@PDMS electrode that shows excellent strain rate (95 %) and durability (1500 cycles) in tensile and fatigue tests. Additionally, electrochemical evaluations are implemented to measure the performance of anode and cathode fabricated with BP@PDMS. In anode including 1,10-phenanthroline-5,6-dione and glucose dehydrogenase, maximum reactivity of glucose oxidation is 1.05 mA/cm2, while in cathode including bilirubin oxidase, that of oxygen reduction is 0.61 mA/cm2. Regarding flexibility, anode and cathode are little affected by current density irrespective of bending angle, proving that the fabricated anode and cathode have good flexibility. To emulate the behavior of EBFCs in actual blood vessel, EBFCs are implanted in TABV cell kit, fueling sheep blood. Observed open circuit voltage of 0.59 V and maximum power of 26 μW reveals that fabricated EBFCs have superior potential to be considered as power sources for implantable devices.

Flexible resistive memory device with egg-albumen/HfO x hybrid bilayer: fabrication and modeling of its switching variations

Egg-albumen, a natural polymer, in bilayer combination with ultrathin HfO x is explored as an active switching layer component in flexible resistive random access memory devices. The fabricated devices have shown excellent switching characteristics with a current on/off ratio of greater than 104, stable retention of both low resistance and high resistance states, reliable multiple cycle switching, and very low switching power (with set power as 0.5 µW and reset power as 3.1 mW). To investigate the electro-mechanical stability, devices were bent with different bending radii and it was found that negligible degradation in device performance was observed until a 5 mm bending radius. Furthermore, a simple mathematical model is used to simulate the devices’ characteristics and the values of fitting parameters were extracted with a root mean square error of less than 4.5%. Moreover, a switching variation was introduced by utilizing variations of the physical parameters, and a near practical physics based mathematical device model was demonstrated which can enable the strengthening of simulation capabilities for exploration of unique flexible resistive memory devices and related circuits.

Filter paper as electrolyte flow transport using vaporized methanol as fuel in a microfluidic fuel cell: Experimental and numerical simulation

In this work, we present a design of a paper-based microfluidic fuel cell (μFC), which employs the spontaneous capillary flow of reactant solutions in a filter paper to accomplish passive conveyance of the fuel and oxidant. This self-pumping device uses methanol vapor as a fuel. The gas phase in the microfluidic fuel cell increases the fuel supply to the anode due to a higher diffusion coefficient of 1.5 ​× ​10−5 ​m2 ​s−1 compared with 5 ​× ​10−9 ​m2 ​s−1 for liquid phase. An air-breathing cathode is incorporated to paper-based μFC through which atmospheric oxygen is continuously supplied. The paper-based μFC performance is studied by polarization curves and chronoamperometry to determinate the power output and stability. Peak power of 1.49 ​mW and a stable current of 1.35 ​mA at 0.35 ​V for 28 ​h can be achieved with this prototype under room temperature. To interpret the device performance a numerical model is developed and validated with the experimental polarization curve. The fuel and oxidant concentration profiles in the electrodes from the model demonstrates a constant species availability at the cathode and anode and explains the stable current obtained in the experimental measurements. Subsequently, a stack of four MμFCFP was developed and evaluated in both series and parallel connections. In the parallel configuration, a maximum open circuit potential (OCP) of 0.69 ​V with a maximum current and power output of 34.53 ​mA and 4.14 ​mW are delivered, respectively. Conversely, in the series connection, a total current of 7.35 ​mA, an OCP of 2.39 ​V and a maximum power of 3.57 ​mW are reached. As a proof of concept, the stack successfully operates a 3 green LEDs array, each requiring a 2.1–2.5 ​V and 4.2–5 ​mW power to function, for a continuous duration of 3 ​h.

A 2.25 ppm/°C High-Order Temperature-Segmented Compensation Bandgap Reference

This paper presents a bandgap reference (BGR) with high-order temperature-segmented compensation. The compensation signal is generated using the voltage difference between two bipolar junction transistor (BJT) emitter bases, each of which individually loads a proportional-to-absolute temperature (PTAT) current and a zero-to-absolute temperature (ZTAT) current. The proposed BGR achieves a low-temperature coefficient (TC) over a wide temperature range. Simulations using the 0.18 μm Bipolar-CMOS-DMOS process show a typical TC of 2.25 ppm/°C from −40 °C to 125 °C. With an active area of 0.07986 mm2, it consumes 36 μW power under an operating voltage of 1 V. The integrated output noise from 0.1 Hz to 10 Hz is 81.1 μV.

A Hybrid Soft Sensor Model for Measuring the Oxygen Content in Boiler Flue Gas.

As an indispensable component of coal-fired power plants, boilers play a crucial role in converting water into high-pressure steam. The oxygen content in the flue gas is a crucial indicator, which indicates the state of combustion within the boiler. The oxygen content not only affects the thermal efficiency of the boiler and the energy utilization of the generator unit, but also has adverse impacts on the environment. Therefore, accurate measurement of the flue gas's oxygen content is of paramount importance in enhancing the energy utilization efficiency of coal-fired power plants and reducing the emissions of waste gas and pollutants. This study proposes a prediction model for the oxygen content in the flue gas that combines the whale optimization algorithm (WOA) and long short-term memory (LSTM) networks. Among them, the whale optimization algorithm (WOA) was used to optimize the learning rate, the number of hidden layers, and the regularization coefficients of the long short-term memory (LSTM). The data used in this study were obtained from a 350 MW power generation unit in a coal-fired power plant to validate the practicality and effectiveness of the proposed hybrid model. The simulation results demonstrated that the whale optimization algorithm-long short-term memory (WOA-LSTM) model achieved an MAE of 0.16493, an RMSE of 0.12712, an MAPE of 2.2254%, and an R2 value of 0.98664. The whale optimization algorithm-long short-term memory (WOA-LSTM) model demonstrated enhancements in accuracy compared with the least squares support vector machine (LSSVM), long short-term memory (LSTM), particle swarm optimization-least squares support vector machine (PSO-LSSVM), and particle swarm optimization-long short-term memory (PSO-LSTM), with improvements of 4.93%, 4.03%, 1.35%, and 0.49%, respectively. These results indicated that the proposed soft sensor model exhibited more accurate performance, which can meet practical requirements of coal-fired power plants.

FPGA Implementation of Power-efficient Multipliers for Digital Signal Processing Applications

Background:: Higher power consumption raises chip temperature because it draws more current from the power source, which directly affects how long the batteries survive in portable devices. High temperature affects the dependability and functionality of a circuit, requiring more complex packaging and cooling strategies. One of the most significant challenges in VLSI design is power consumption. The power consumption of the circuit rises with both transistor density and chip complexity. In addition, one of the essential building blocks of hardware in the majority of VLSI applications and digital signal processing systems is the multiplier. Aims and objective:: This study aimed to design and compare array multiplier, Vedic multiplier, and Wallace tree multiplier using variable bit lengths. Methodology:: In this paper, authors designed array multiplier, Vedic multiplier, and Wallace tree multiplier using variable bit lengths. For comparison, the VIVADO tool was used to simulate and synthesize multiplier outputs. Results:: Wallace tree multipliers resulted in 31.153mW, 13.220mW, 4.099mW, and 0.988 mW of power dissipation for 16-bit, 8-bit, 4-bit, and 2-bit, respectively. The best multiplier was designed using different logic like AOI, OAI, NAND-NAND, and NOR-NOR and was compared based on power dissipation. It was observed that 2.256mW power dissipation was observed for NOR-NOR logic, which was minimal among other logics. Conclusion:: The 4-bit Wallace multiplier using NOR-NOR logic was used for FPGA implementation, which can be used in digital signal processing applications.

A High Gain Concurrent Dual-band Low-Noise Amplifier in 130-nm BiCMOS Technology

This paper presents a fully integrated concurrent 15/30-GHz dual-band low-noise amplifier (LNA). The proposed concurrent LNA IC is designed and simulated in 130-nm BiCMOS technology. The new passive LC notch filter is proposed to realize high gain and low noise figure over dual-band frequency, simultaneously. The simulated BiCMOS LNA IC has exhibited peak gains of 30.1/23.7 dB at 15/30-GHz, respectively, with 20-mW power consumption from 1-V supply. The concurrent dual-band LNA achieves noise figure of 2.2/2.9-dB and IIP3 of -18.2/-8.8 dBm at the respective passbands. Therefore, the proposed dual band concurrent LNA IC is applicable to front-end RF receivers for Ku-Band and Ka-Band systems.

Developing Air-Stable n-Type SWCNT-Based Composites with High Thermoelectric and Robust Mechanical Properties for Wearable Electronics.

Flexible organic thermoelectric generators are gaining prominence in wearable electronics, leveraging body heat as an energy source. Their advancement is hindered by the scarcity of air-stable n-type organic materials with robust mechanical properties. This study introduces two new polymers (HDCN4 and HDCN8), created through polycondensation of paraformaldehyde and diamine-terminated poly(ethylene glycol) (PEGDA) with molecular weights of 4000 and 8000 g/mol into single-walled carbon nanotubes (SWCNTs). The resulting HDCN4/SWCNT and HDCN8/SWCNT composites show impressive power factors of 225.9 and 108.2 μW m-1 K-2, respectively, and maintain over 90% in air for over four months without encapsulation. The HDCN4/SWCNT composite also demonstrates significant tensile strength (33.2 MPa) and flexibility (up to 10% strain), which is currently the best mechanically n-type thermoelectric material with such a high power factor reported in the literature. A thermoelectric device based on HDCN4/SWCNT generates 4.2 μW of power with a 50 K temperature difference. Additionally, when used in wearable temperature sensors, these devices exhibit high mechanical reliability and a temperature resolution of 0.1 K. This research presents a viable method to produce air-stable n-type thermoelectric materials with excellent performance and mechanical properties.

An Efficient RTL Design for a Wearable Brain–Computer Interface

This article proposes an efficient and accurate embedded motor imagery-based brain–computer interface (MI-BCI) that meets the requirements for wearable and real-time applications. To achieve a suitable accuracy considering hardware constraints, we explore BCI transducer algorithms, among which Infinite impulse response (IIR) filter, common spatial pattern, and support vector machine are used to preprocess, extract features, and classify data, respectively. With our hardware implementation of these tasks, we have achieved an accuracy of 77%. Our system is designed at register transfer level (RTL) targeting an ASIC implementation, which significantly decreases power consumption, latency, and area compared to the state-of-the-art (SoA) architectures for embedded BCI systems. To this end, we fold IIR filters using time-shared and RAM-based techniques and use hardware-friendly algorithms for the implementation of other tasks. The RTL design is realized on 45 nm CMOS technology consuming 4 mW power and 0.25 mm2 area, which outperforms the SoA platforms for embedded BCI systems. To further illustrate the outperformance of our design, the proposed architecture is implemented on Virtex-7 field program gate array as a prototyping platform consuming 6 μJ energy with 1.52% area utilization.

A 10.5 ppm/°C Modified Sub-1 V Bandgap in 28 nm CMOS Technology with Only Two Operating Points

Reference voltage/current generation is essential to the Analog circuit design. There have been several ways to generate quality reference voltage using bandgap reference (BGR) and there are mainly two types: current mode and voltage mode. The current-mode bandgap reference (CBGR) is widely accepted in industry due to having an output voltage which is below 1 V. However, its drawbacks include a lack of proportional to absolute temperature (PTAT) current availability, a large silicon area, multiple operating points, and a large temperature coefficient (TC). In this paper, various operating points are explained in detail with diagrams. Similar to the conventional voltage mode bandgap reference (VBGR) circuits, modifications of the existing circuits with only two operating points have also been proposed. Moreover, the proposed BGR occupies a much smaller area due to eliminating the complimentary to absolute temperature (CTAT) current-generating resistor. A new self-biased opamp was introduced to operate from a 1.05 V supply, reducing systematic offset and TC of the BGR. The proposed solution has been implemented in 28 nm CMOS TSMC technology, and extraction simulations were performed to prove the robustness of the proposed circuit. The targeted mean BGR output is 500 mV, and across the industrial temperature range (−40 to 125 °C), the simulated TC is approximately 10.5 ppm/°C. The integrated output noise within the observable frequency band is 19.6 µV (rms). A 200-point Monte Carlo simulation displays a histogram with a 2.6 mV accuracy of 1.2% (±3-sigma). The proposed BGR circuit consumes 32.8 µW of power from a 1.05 V supply in a fast process and hot (125 °C) corner. It occupies a silicon area of 81 × 42 µm (including capacitors). This design can aim for use in biomedical and sensor applications.

Variations in the characteristics of low-voltage logic gates based on vertical silicon nanotransistors with a conical channel

The issues of numerical simulation of fluctuations in the electro-physical characteristics of low-voltage logic gates based on silicon vertical nanotransistors with a surrounding gate with a conical geometry are discussed. Instrumentation and technological models of n- and p-types of conductivity of conical nanotransistors have been developed for the case when the conical working area is set as follows. On the source side, for a large diameter, the condition for suppressing short-channel effects is not fulfilled, and on the drain side, for a small diameter, it is fulfilled. Such transistor structures in the control voltage range from 0 to 0.6 V are characterized by a higher transistor current, a low leakage current and a slope of the subthreshold characteristic close to the theoretical limit. Prototypes of transistors with optimal parameters for the synthesis of logic gates with a gate length of 25 nm and a working area diameter ratio of 8.5/10 nm have been selected. The fluctuation range of the drain current is distributed according to the normal law for both types of transistors with an average of 12.25 µA for the n-type and 6.5 µA for the p-type and a standard deviation of 19.3. The total spread is 3.06 µA and 1.45 µA, or 25% and 22%, respectively. To offset the influence of the considered mechanisms, it is recommended to limit the level of doping of the drain/source regions and use relatively large cross-sections of the working area from the range of possible ones. This will ensure stable electro-physical characteristics of transistors with high parry of short-channel effects. An instrument-technological model of an inverter based on vertically arranged n- and p-type transistors with an optimized diameter ratio has been developed. Variations of electro-physical characteristics in the range of control voltages 0...0.6 V and a clock frequency of 20 GHz are numerically investigated. In all cases, the prototypes demonstrate picosecond delays and low power consumption. The valve model predicts a general fluctuation of switching times of 18% at average values of 1.6 and 0.8 ps, respectively, active power of 16% at an average value of 0.2 µW and static power of 11% at an average value of 0.7 pW. The results of the study can be used in the design of digital circuits to expand the SOA zone.

Tracking Photovoltaics Systems at Mountain Heights

The expansion of the use of solar energy in most cases depends on the energy capabilities of each specific country. In Tajikistan, where 93% of the territory is mountains, it is necessary to build solar power plants high in the mountains. At mountain heights, the performance of panels increases in winter, in addition, the snow cover that reflects the sun's rays also contributes to an increase in the efficiency of solar panels. Experts note that solar panels receive less radiation in valleys, as clouds and fogs often prevent the passage of sunlight. At the heights of the mountains, there is no air pollution and, as a result, a longer operating time of the solar power plant. In the conditions of Tajikistan, one more drawback of solar stations in the valleys should be added - this is the rapid pollution of the panels due to dust storms in the summer-autumn period. The Chinese company Sun Tech Power Holdings will build a 10 MW power plant in Tibet at an altitude of 4000 meters above sea level.

Thermal-Hydraulic Analysis of Pebble Bed High Temperature Gas-Cooled Reactor After Shutdown Based on FLUENT Software

In order to provide a reliable tool for thermal-hydraulic simulation of pebble bed high temperature gas-cooled reactors (HTGRs), a two-dimensional model was developed based on the porous media model and user-defined scalar (UDS) function of FLUENT software. Then, the model was applied to the numerical simulation of the shutdown test of the 10 MW high temperature gas-cooled test reactor (HTR-10) at 9 MW power level, and the temperature distribution and flow field distribution in the reactor were obtained and compared with the results of the experimental data. The reliability of the model in this paper was verified. Based on the model, the effects of the water-cooled panel temperature and the initial core temperature on the thermal-hydraulic characteristics of HTR-10 after shutdown were further explored. The results show that there is a decoupling phenomenon between the residual heat transfer within the core and the heat dissipation of the pressure vessel. The initial core temperature has relatively little effect on the heat dissipation and maximum temperature of the pressure vessel, but it has a significant impact on the thermal characteristics of the core area.

Design and Simulation of an Ultra-Low-Power Hydrogen Sulfide Gas Sensor with a Cantilever Structure.

Metal oxide gas sensors usually require a few tens of milliwatts of power consumption to operate at high temperature, which limits their application in mobile and portable devices. Here, we proposed a cantilever structure to build an ultra-low power gas sensor for hydrogen sulfide gas detection. By employing a nano-film size effect to reduce the thermal conductivity of the material, and self-heated corrugation configuration, the power consumption of the gas sensor is significantly reduced. Through numerical analysis and finite element simulation, two different gas sensors were designed and the power consumption and stress distribution were analyzed and optimized. Under the operating temperature of 200 °C, only 0.27 mW power is consumed, the stress value is less than 250 MPa and the displacement is a few hundred of nanometers. The results serve as a guide and reference for ultra-low power MEMS device designs.