Low-frequency oscillation of train-network system considering traction power supply mode

The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.

A Hybrid Integrated and Low-Cost Multi-Chip Broadband Doherty Power Amplifier Module for 5G Massive MIMO Application

In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)application.An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small area.The proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 dBm.The gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 GHz.The measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.

Design of a Low Power Low-Noise Amplifier with Improved Gain/Noise Ratio

This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhance gain, minimize noise levels, and uphold low power consumption. The progression includes a shift to a cascode structure to further refine LNA parameters. Ultimately, with a 1.8 V bias, the achieved performance showcases a gain-to-noise figure ratio of 16 dB/0.5 dB, an IIP3 linearity at 5.1 dBm, and a power consumption of 3 mW. This architecture is adept at operating across a wide frequency band spanning from 0.5 GHz to 6 GHz, rendering it applicable in diverse RF scenarios.

A class of quasilinear equations with-1 powers

This paper deals with quasilinear elliptic equations of singular growth like-Δu-uΔ(u^(2))=a(x)u^(-1).We establish the existence of positive solutions for general a(x)∈L^(p)(Ω),p>2,whereΩis a bounded domain inℝ^(N)with N≥1.

Short-Term Photovoltaic Power Prediction Based onMulti-Stage Temporal Feature Learning

Harnessing solar power is essential for addressing the dual challenges of global warming and the depletion of traditional energy sources.However,the fluctuations and intermittency of photovoltaic(PV)power pose challenges for its extensive incorporation into power grids.Thus,enhancing the precision of PV power prediction is particularly important.Although existing studies have made progress in short-term prediction,issues persist,particularly in the underutilization of temporal features and the neglect of correlations between satellite cloud images and PV power data.These factors hinder improvements in PV power prediction performance.To overcome these challenges,this paper proposes a novel PV power prediction method based on multi-stage temporal feature learning.First,the improved LSTMand SA-ConvLSTMare employed to extract the temporal feature of PV power and the spatial-temporal feature of satellite cloud images,respectively.Subsequently,a novel hybrid attention mechanism is proposed to identify the interplay between the two modalities,enhancing the capacity to focus on the most relevant features.Finally,theTransformermodel is applied to further capture the short-termtemporal patterns and long-term dependencies within multi-modal feature information.The paper also compares the proposed method with various competitive methods.The experimental results demonstrate that the proposed method outperforms the competitive methods in terms of accuracy and reliability in short-term PV power prediction.

Short-TermWind Power Forecast Based on STL-IAOA-iTransformer Algorithm:A Case Study in Northwest China

Accurate short-term wind power forecast technique plays a crucial role in maintaining the safety and economic efficiency of smart grids.Although numerous studies have employed various methods to forecast wind power,there remains a research gap in leveraging swarm intelligence algorithms to optimize the hyperparameters of the Transformer model for wind power prediction.To improve the accuracy of short-term wind power forecast,this paper proposes a hybrid short-term wind power forecast approach named STL-IAOA-iTransformer,which is based on seasonal and trend decomposition using LOESS(STL)and iTransformer model optimized by improved arithmetic optimization algorithm(IAOA).First,to fully extract the power data features,STL is used to decompose the original data into components with less redundant information.The extracted components as well as the weather data are then input into iTransformer for short-term wind power forecast.The final predicted short-term wind power curve is obtained by combining the predicted components.To improve the model accuracy,IAOA is employed to optimize the hyperparameters of iTransformer.The proposed approach is validated using real-generation data from different seasons and different power stations inNorthwest China,and ablation experiments have been conducted.Furthermore,to validate the superiority of the proposed approach under different wind characteristics,real power generation data fromsouthwestChina are utilized for experiments.Thecomparative results with the other six state-of-the-art prediction models in experiments show that the proposed model well fits the true value of generation series and achieves high prediction accuracy.

Investigation of a NO_(x) emission from coal power plants in Texas, United States and its impact on the environment

Texas is the largest state by area in the US after Alaska,and one of the top states in the production and consumption of electricity with many coal-fired plants.Coal-fired power plants emit greater than 70% of pollutants in the energy sector.When coal is burned to produce electricity,nitrogen oxides(NO_(x))are released into the air,one of the main pollutants that threaten human health and lead to a large number of premature deaths.The key to effective air quality management is the strict compliance of all plants with emission standards.However,not all Texas coal plants have the environmental equipment to lower pollutant emissions.Nitrogen dioxide(NO2)observations from the TROPOspheric Monitoring Instrument(TROPOMI)were used to evaluate the emissions for Texas power plants.Data from both the Emissions and Generation Resource Integrated Database(EGRID)and the Emissions Database for Global Atmospheric Research(EDGAR)were used to examine emissions.It was found that NOx emissions for Texas power plants range from 1.53 kt/year to 10.99 kt/year,with the Martin Lake,Limestone and Fayette Power Project stations being the top emitters.WA Parish and Martin Lake stations have the strongest NOx fluxes,with both exhibiting significant seasonal variability.Comparisons of bottom-up inventories for EDGAR and EGRID show a high correlation(r=0.956)and a low root mean square error(0.766).A more reasonable control policy would lead to much reduced NOx emissions.

Generation of low-temperature plasma by pulse-width modulated signals and monitoring of the interaction thereof with the surface of objects

The article discusses the use of pulse-width modulation signals to generate low-temperature atmospheric plasma in an inert gas environment.The results of studies of the energy consumption of a low-temperature plasma generation system depending on the duty rate,as well as the pulse repetition rate,are presented.The operating modes of the system have been established,in which a minimum of energy consumption is achieved.The issues of evaluating the interaction of plasma with objects based on the analysis of changes in signal parameters in the high-voltage circuit of the generator are also considered.

A low-phase-noise and low-power crystal oscillator for RF tuner

A 37. 5 MHz differential complementary metal oxide semiconductor （CMOS） crystal oscillator with low power and low phase noise for the radio frequency tuner of digital radio broadcasting digital radio mondiale （DRAM） and digital audio broadcasting （DAB） systems is realized and characterized. The conventional cross-coupled n-type metal oxide semiconductor （NMOS） transistors are replaced by p-type metal oxide semiconductor （PMOS） transistors to decrease the phase noise in the core part of the crystal oscillator. A symmetry structure of the current mirror is adopted to increase the stability of direct current. The amplitude detecting circuit made up of a single- stage CMOS operational transconductance amplifier （OTA） and a simple amplitude detector is used to improve the current accuracy of the output signals. The chip is fabricated in a 0. 18- pxn CMOS process, and the total chip size is 0. 35 mm x 0. 3 mm. Under a supply voltage of 1.8 V, the measured power consumption is 3.6 mW including the output buffer for 50 testing loads. The proposed crystal oscillator exhibits a low phase noise of - 134. 7 dBc/Hz at 1-kHz offset from the center frequency of 37. 5 MHz.

An Ultra-Low-Power Embedded EEPROM for Passive RFID Tags

An ultra-low-power,256-bit EEPROM is designed and implemented in a Chartered 0.35μm EEPROM process. The read state power consumption is optimized using a new sense amplifier structure and an optimized control circuit. Block programming/erasing is achieved using an improved control circuit. An on silicon program/erase/read access time measurement design is given. For a power supply voltage of 1.8V,an average power consumption of 68 and 0.6μA for the program/erase and read operations,respectively,can be achieved at 640kHz.

Low-Power CMOS IC for Function Electrical Stimulation of Nerves

A low-power IC for function electrical stimulation （FES） of nerves is designed for an implantable system and fabricated in CSMC＇s 0.6μm CMOS technology. The IC can be used for stimulating animals＇ spinal nerve bundles and other nerves connected with a cuff type electrode. It consists of a pre-amplifier,a main amplifier,and an output stage. According to the neural signal spectrum,the bandwidth of the FES signal generator circuit is defined from 1Hz to 400kHz. The gain of the circuit is about 66dB with an output impedance of 900. The 1C can function under a single supply voltage of 3-5V. A rail-to-rail output stage helps to use the coupled power efficiently. The measured time domain performance shows that the bandwidth and the gain of the IC agree with the design. The power consumption is lower than 6mW.

A Low-Power-Consumption 9bit 10MS/s Pipeline ADC for CMOS Image Sensors

A low-power-consumption 9bit 10MS/s pipeline ADC,used in a CMOS image sensor,is proposed. In the design, the decrease of power consumption is achieved by applying low-power-consumption and large-output-swing amplifiers with gain boost structure, and biasing all the cells with the same voltage bias source, which requires careful layout design and large capacitors. In addition,capacitor array DAC is also applied to reduce power consumption,and low threshold voltage MOS transistors are used to achieve a large signal processing range. The ADC was implemented in a 0.18μm 4M-1 P CMOS process,and the experimental results indicate that it consumes only 7mW, which is much less than general pipeline ADCs. The ADC was used in a 300000 pixels CMOS image sensor.

A Low-Power High-Frequency CMOS Peak Detector

A low-power,high-frequency CMOS peak detector is proposed. This detector can detect RF signal and base-band signal peaks. The circuit is designed using SMIC 0.35μm standard CMOS technology. Both theoretical calculations and post simulations show that the detection error is no more than 2% for various temperatures and processes when the input amplitude is larger than 400mV. The detection bandwidth is up to 10GHz, and its static current dissipation is less than 20μA.

A Low-Voltage,High Efficiency Power Generation Structure for UHF RFID

This paper presents a new power generation structure that can provide DC energy for passive UHF RFID with high sensitivity and high efficiency. The structure is designed with 0.18μm standard CMOS technology, including two charge pumps,a current reference, and a group of bias circuits. Low-voltage performance is improved thanks to the bias structure,which eliminates the threshold voltage drop and body-effect of conventional circuits. A 350mV minimum input level is required to generate a 1.5V power supply for a 100k~ load with power conversion efficiency （PCE） of 22%. PCE up to 29.8% is achieved with a 60kΩ load. Simulation results show that the new circuit is superior to conventional charge pumps.

夏热冬冷地区Low-E玻璃节能效果研究

目的为了解决夏热冬冷地区民宿玻璃幕墙节能设计过程中,对于性能接近的玻璃种类的选择问题。方法采用DeST模拟软件建立一个二层民宿的物理模型,依据《河南省公共建筑节能设计标准》选择满足要求的双玻Low-E玻璃和三玻Low-E玻璃。通过控制对负荷影响较大的3个参数:传热系数、太阳能总透射比、红外热能总透射比,来保持其控制参数相同或近似相等,再基于当地典型气象年的实测数据,采用DeST模拟软件对该民宿建筑进行全年能耗计算,并通过加拿大采暖季能耗评价体系(ER)与制冷季能耗评价体系(ERC)进行能耗分析,观察节能效果。结果表明将双玻用三玻进行改造后,ERC值为3.57,说明三玻两腔单Low-E中空(空气)玻璃在制冷季节能效果更好;ER值为-1.83,说明双玻单Low-E中空(氩气)玻璃在采暖季节能效果更优。三玻两腔单Low-E中空(空气)玻璃相对于双玻单Low-E中空(氩气)玻璃成本贵了60元/m^(2),每年带来的经济效益为1.92元/m^(2),需要至少30年才能完成成本回收,综合考虑各种因素,双玻单Low-E中空玻璃才是首选。结论研究结果为夏热冬冷地区民宿建筑玻璃幕墙种类的选择提供了一种新的方法,具有重要的参考价值和借鉴意义。

Nested Miller Active-Capacitor Frequency Compensation for Low-Power Three-Stage Amplifiers

A new frequency compensation technique for low-power, area-efficient multistage amplifiers is introduced. Using nested active capacitors, our scheme achieves better bandwidth-to-power and slew-rate-to-power performances than previous works. Implemented in standard 0.35μm CMOS technology, our three-stage amplifier achieves 105dB DC gain, 3.3M GBW,68 phase margin, and 2.56V/μs average slew rate under a 150pF capacitive load. All of these are realized with only 40μW power consumption under a 2V power supply,with very small compensation capacitors.

A Low-Voltage,Low-Power CMOS High Dynamic Range dB-Linear VGA for Super Heterodyne Receivers

This paper presents a low-voltage low-power variable gain amplifier,which is applied in the automatic gain control loop of a super heterodyne receiver. Six stages are cascaded to provide an 81dB digitally controlled gain range in a 3dB step. The gain step error is less than 0.5dB. It operates at an intermediate frequency of 300kHz, and the power consumption is 1.35mW from a 1.8V supply. The prototype chip is implemented in a TSMC＇s 0.18μm 1P6M CMOS process and occupies approximately 0.24mm^2 . It is very suitable for portable wire- less communication systems. The measurement results agree well with the system requirements.

A Low-Power,Single-Poly,Non-Volatile Memory for Passive RFID Tags

Single-poly,576bit non-volatile memory is designed and implemented in an SMIC 0.18μm standard CMOS process for the purpose of reducing the cost and power of passive RFID tag chips. The memory bit cell is designed with conventional single-poly pMOS transistors, based on the bi-directional Fowler-Nordheim tunneling effect, and the typical program/erase time is 10ms for every 16bits. A new ,single-ended sense amplifier is proposed to reduce the power dissipation in the current sensing scheme. The average current consumption of the whole memory chip is 0.8μA for the power supply voltage of 1.2V at a reading rate of 640kHz.

ICU患者置入Power PICC导管特殊异位原因分析

目的:探讨ICU患者置入Power PICC导管后头端反折向上至同侧和对侧锁骨下静脉、头臂静脉等特殊异位的相关因素。方法:回顾性分析2021年9月至2022年9月某三甲医院ICU 520例PICC置管患者,通过胸部X线确定PICC导管头端反折向上至对侧和同侧锁骨下静脉、头臂静脉的患者,分析其特殊异位发生因素。结果:胸部X线结果显示25例患者PICC管头端反折向上异位至对侧和同侧锁骨下静脉、头臂静脉或颈内静脉,异位发生率4.8%,不同静脉置管反折异位发生率相比差异无统计学意义,P>0.05。结论:ICU患者PICC置入发生导管头端反折向上至同侧和对侧锁骨下静脉、头臂静脉等特殊异位的发生因素较多,包括同时留置CVC或血透管、正在滴注或泵入多种药物、PICC管头端异位的隐匿性、导管材质、自身疾病及机械通气等危险因素。

Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate

Retaining or improving periodontal ligament （PDL） function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation （LPLI） on the proliferation and osteogenic differentiation of human PDL （hPDL） cells. Cultured hPDL cel Is were irradiated （660 nm） daily with doses of O, 1, 2 or 4 J .cm-2. Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide （MTT） assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase （ALP） activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction （RT-PCR）. Our data showed that LPLI at a dose of 2 J.cm-2 significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J.cm-2 showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate （cAMP） is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.