Performance of pulsed plasma thruster at low discharge energy

As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.

The study of intelligent algorithm in particle identification of heavy-ion collisions at low and intermediate energies

Traditional particle identification methods face timeconsuming,experience-dependent,and poor repeatability challenges in heavy-ion collisions at low and intermediate energies.Researchers urgently need solutions to the dilemma of traditional particle identification methods.This study explores the possibility of applying intelligent learning algorithms to the particle identification of heavy-ion collisions at low and intermediate energies.Multiple intelligent algorithms,including XgBoost and TabNet,were selected to test datasets from the neutron ion multi-detector for reaction-oriented dynamics(NIMROD-ISiS)and Geant4 simulation.Tree-based machine learning algorithms and deep learning algorithms e.g.TabNet show excellent performance and generalization ability.Adding additional data features besides energy deposition can improve the algorithm’s performance when the data distribution is nonuniform.Intelligent learning algorithms can be applied to solve the particle identification problem in heavy-ion collisions at low and intermediate energies.

Low Carbon Building Design Optimization Based on Intelligent Energy Management System

The construction of relevant standards for building carbon emission assessment in China has just started,and the quantitative analysis method and evaluation system are still imperfect,which hinders the development of low-carbon building design.Therefore,the use of intelligent energy management system is very necessary.The purpose of this paper is to explore the design optimization of low-carbon buildings based on intelligent energy management systems.Based on the proposed quantitative method of building carbon emission,this paper establishes the quota theoretical system of building carbon emission analysis,and develops the quota based carbon emission calculation software.Smart energy management system is a low-carbon energy-saving system based on the reference of large-scale building energy-saving system and combined with energy consumption.It provides a fast and effective calculation tool for the quantitative evaluation of carbon emission of construction projects,so as to realize the carbon emission control and optimization in the early stage of architectural design and construction.On this basis,the evaluation,analysis and calculation method of building structure based on carbon reduction target is proposed,combined with the carbon emission quota management standard proposed in this paper.Taking small high-rise residential buildings as an example,this paper compares and analyzes different building structural systems from the perspectives of structural performance,economy and carbon emission level.It provides a reference for the design and evaluation of low-carbon building structures.The smart energy management system collects user energy use parameters.It uses time period and time sequence to obtain a large amount of data for analysis and integration,which provides users with intuitive energy consumption data.Compared with the traditional architectural design method,the industrialized construction method can save 589.22 megajoules(MJ)per square meter.Based on 29270 megajoules(MJ)per ton of standard coal,the construction area of the case is about 8000 m2,and the energy saving of residential buildings is 161.04 tons of standard coal.This research is of great significance in reducing the carbon emission intensity of buildings.

Application of Dual-Energy X-Ray Image Detection of Dangerous Goods Based on YOLOv7

X-ray security equipment is currently a more commonly used dangerous goods detection tool, due to the increasing security work tasks, the use of target detection technology to assist security personnel to carry out work has become an inevitable trend. With the development of deep learning, object detection technology is becoming more and more mature, and object detection framework based on convolutional neural networks has been widely used in industrial, medical and military fields. In order to improve the efficiency of security staff, reduce the risk of dangerous goods missed detection. Based on the data collected in X-ray security equipment, this paper uses a method of inserting dangerous goods into an empty package to balance all kinds of dangerous goods data and expand the data set. The high-low energy images are combined using the high-low energy feature fusion method. Finally, the dangerous goods target detection technology based on the YOLOv7 model is used for model training. After the introduction of the above method, the detection accuracy is improved by 6% compared with the direct use of the original data set for detection, and the speed is 93FPS, which can meet the requirements of the online security system, greatly improve the work efficiency of security personnel, and eliminate the security risks caused by missed detection.

ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.

Effective data transmission through energy-efficient clustering and Fuzzy-Based IDS routing approach in WSNs

Wireless sensor networks(WSN)gather information and sense information samples in a certain region and communicate these readings to a base station(BS).Energy efficiency is considered a major design issue in the WSNs,and can be addressed using clustering and routing techniques.Information is sent from the source to the BS via routing procedures.However,these routing protocols must ensure that packets are delivered securely,guaranteeing that neither adversaries nor unauthentic individuals have access to the sent information.Secure data transfer is intended to protect the data from illegal access,damage,or disruption.Thus,in the proposed model,secure data transmission is developed in an energy-effective manner.A low-energy adaptive clustering hierarchy(LEACH)is developed to efficiently transfer the data.For the intrusion detection systems(IDS),Fuzzy logic and artificial neural networks(ANNs)are proposed.Initially,the nodes were randomly placed in the network and initialized to gather information.To ensure fair energy dissipation between the nodes,LEACH randomly chooses cluster heads(CHs)and allocates this role to the various nodes based on a round-robin management mechanism.The intrusion-detection procedure was then utilized to determine whether intruders were present in the network.Within the WSN,a Fuzzy interference rule was utilized to distinguish the malicious nodes from legal nodes.Subsequently,an ANN was employed to distinguish the harmful nodes from suspicious nodes.The effectiveness of the proposed approach was validated using metrics that attained 97%accuracy,97%specificity,and 97%sensitivity of 95%.Thus,it was proved that the LEACH and Fuzzy-based IDS approaches are the best choices for securing data transmission in an energy-efficient manner.

建筑节能设计Low-E玻璃窗的遮阳参数取值分析

节能外窗属于精密工业制品,也是建筑工程外围护结构的重要组成部分。为能降低房间内的夏季太阳得热,工程中通常采用低辐射Low-E玻璃外窗,但由于国家及各地区的技术规范对Low-E玻璃窗的参数取值不尽相同、审图机构的把握尺度不一、门窗厂家的加工技术水平参差不齐,为能解决Low-E玻璃外窗的遮阳参数取值和选型困难的问题,达到概念清晰、数据可靠、便于实施的目的,文中采用公式计算和查表对比的方法,对规范的遮阳参数概念作补充说明,同时结合江苏某住宅项目的工程实践,给出Low-E玻璃窗遮阳参数的取值原则和建议,并认为一般Low-E玻璃的自遮阳系数取值最高不应超过0.60。

LARGE VOLUME IONIZATION CHAMBER USED AS LABORATORY REFERENCE FOR LOW ENERGY X－RAY MEASUREMENT

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Studies on Reducing Nitrogen Excretion: Ⅰ. Net Energy Requirement of Finishing Pigs Maximizing Performance and Carcass Quality Fed Low Crude Protein Diets Supplemented with Crystalline Amino Acids

Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino acids （CAA）. A total of 216 （Exp. 1） and 360 （Exp. 2 ） barrows （ Yorkshire × Landrace× Duroc ） were allotted to one of six treatments （n =6）. The experimental diets were based on corn and soybean meal, and consisted of a high-CP diet that contained approximately 16% CP and 2.50 Mcal/kg of NE as well as five low-CP diets in which the CP level of the diet was reduced by approximately four percentage units but was supplemented with crystalline lysine, methionine, threonine, and tryptophan. The low CP diets provided 2.64, 2.58, 2.50, 2.42, or 2.36 Mcal/kg in Exp. 1 as well as 2.45, 2.40, 2.35, 2.30, or 2.25 Mcai/kg in Exp.2. In Exp. 1, a linear （P=0.03） increase in weight gain was observed with decreasing NE level while the ratio of gain to feed was unaffect- ed （P 〉 0.05） by NE level. There was a linear in-crease （P = 0.01 ） in the percentage of fat-free lean and a linear decrease （ P = 0.03 ） in the percentage of total fat with decreasing NE levels. In Exp. 2, a sig- nificant quadratic （ P = 0.03 ） effect of NE level was observed for weight gain. The ratio of gain to feed demonstrated a significant （P 〈0.01 ） quadratic effect with pigs fed 2.35 and 2.40 Mcal/kg of NE, Pigs fed the diet containing 2.40 Mcal/kg of NE had the lowest percentage of total fat （36. 95% ） and the highest percentage of fat-free lean （49.36%）. The overall results of these experiments indicate that feed- ing either a surplus or a deficiency of NE is detrimen- tal to both pig performance and carcass composition when low CP diets supplemented with CAA are fed. Our results indicate that when the CP content of the diet is reduced by four percentage units and the diet is properly supplemented with CAA, maximum per- formance and carcass quality will be obtained if the diet provides approximately 2.42 Mcal/kg of NE.

Genetic Transformation of Watermelon with Pumpkin DNA by Low Energy Ion Beam-mediated Introduction

The No.601 watermelon (citrullus lanatus) seeds were treated with 25 keV N+ implantation at the dosage of 7.8 ×1016 ions/cm2. After treatment, watermelon seeds were incubated with 380μg/μl pumpkin (Cucubita, maxima Duch) DNA solution at 35 ℃ for 5 hours. By two-generations of selection and resistance screening at seedling stage, one transformed material was selected out, whose rind color is similar to that of the donor pumpkin and whose size of seeds is between that of the donor and the receptor. Using AFLP (amplified fragment length polymorphism) technique, two polymorphic DNA fragments were amplified. This primarily testified that the donor DNA fragments/gene were introduced into the receptor cell and integrated into the genomic DNA of the receptor.

Growth behaviour of low-energy plasma electrolytic oxidation coatings on a magnesium alloy

Plasma electrolytic oxidation(PEO),a promising surface treatment method to improve the corrosion and wear resistance of magnesium and its alloys,operates at high voltages,resulting in a relatively high energy cost.To make the PEO process more economically viable,its energy efficiency needs to be improved.This study investigates the growth behaviour and microstructural characteristics of low-energy PEO coatings on an AM50 magnesium alloy in a concentrated electrolyte containing sodium tetraborate.The surface morphology of the coatings was different from typical PEO coating morphologies and a large voltage oscillation was observed during treatment.Using different characterisation techniques,and based on a micro-discharge model,a correlation was made between the voltage-time behaviour,microdischarge characteristics and the composition and microstructure of the coated samples.The results suggest electrolyte chemistry can somewhat control discharge behaviour,which plays an important role in PEO coating growth.

Study of Biological Effects of Low Energy Ion Implantation on Tomato and Radish Breeding

Biological effects of 30 keV low energy nitrogen ion implantation on the seeds of five types of tomato and one type of radish were investigated. Results showed that low energy ions have different effects on different vegetables. The whole dose-response curve of the germination ratio did not take on ＂the shape of saddle＂, but was a rising and falling waveform with the increase or decrease in ion implantation. In the vegetable of Solanaceae, two outstanding aberrant plants were selected from M1 of Henan No.4 tomato at a dose of 7x 1017 nitrogen ions/cm2, which had thin-leaves, long-petal and nipple tip fruit stably inherited to Mr. Furthermore the analysis of the isozyme showed that the activity of the mutant tomato seedling was distinct in quantity and color. In Raphanus sativus L., the aberrances were obvious in the mutant of radish 791 at a dose of 5×10^17 nitrogen ions/cm^2, and the weight of succulent root and the volume of growth were over twice the control＇s. At present, many species for breeding have been identified in the field and only stable species have been selected for the experiment of production. It is evident that the low energy ion implantation technology has clear effects on vegetables＇ genetic improvement.

Efficacy of low-energy selective laser trabeculoplasty on the treatment of primary open angle glaucoma

AIM: To investigate the efficacy of low-energy selective laser trabeculoplasty(SLT) on the treatment of primary open angle glaucoma(POAG) patients.METHODS: Outpatients with POAG who underwent 360-degree SLT using an initial energy of 0.3 mJ(total energy of 30-40 mJ) were reviewed retrospectively from September 2011 to January 2018.RESULTS: Eight-six eyes of 44 POAG patients underwent 360-degree SLT using initial energy of 0.3 mJ and were followed up regularly. The total energy used was 32.5±2.5 mJ(23-40 mJ, 105±6 spots). The average pretreatment intraocular pressure(IOP) was 19.8±3.9 mm Hg. At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 16.9±3.3, 16.5±3.3, 17.1±3.4, 16.6±3.5, 16.5±2.8, which were significantly lower than that before treatment(P<0.001). The patients in the SLT success group were found to be younger than those in the SLT failure group. After SLT, 59 eyes that maintained pretreatment medications were defined as the drug retention group. The pre-SLT IOP was 20.1±3.7 mm Hg.At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 17.3±3.6, 16.6±3.5, 17.2±3.6, 16.9±3.8 and 16.5±2.9, respectively. Twenty-seven eyes that required reduced drugs were defined as the drug reduction group. The pre-SLT IOP was 19.2±4.4 mm Hg. At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 16.1±2.6, 16.5±3.1, 16.8±2.9, 16.0±2.6 and 16.3±2.4, respectively. Compared with the pretreatment IOPs, the post-SLT IOPs were significantly lower in drug retention group and drug reduction group. The patients in the drug reduction group were found to be younger than those in the drug retention group.CONCLUSION: Low-energy SLT is safe and effective for POAG patients during a 2-year follow-up. Younger POAG patients may obtain better results after low-energy SLT treatment.

Prediction of the Charpy V-notch impact energy of low carbon steel using a shallow neural network and deep learning

The impact energy prediction model of low carbon steel was investigated based on industrial data. A three-layer neural network, extreme learning machine, and deep neural network were compared with different activation functions, structure parameters, and training functions. Bayesian optimization was used to determine the optimal hyper-parameters of the deep neural network. The model with the best performance was applied to investigate the importance of process parameter variables on the impact energy of low carbon steel. The results show that the deep neural network obtains better prediction results than those of a shallow neural network because of the multiple hidden layers improving the learning ability of the model. Among the models, the Bayesian optimization deep neural network achieves the highest correlation coefficient of 0.9536, the lowest mean absolute relative error of 0.0843, and the lowest root mean square error of 17.34 J for predicting the impact energy of low carbon steel. Among the variables, the main factors affecting the impact energy of low carbon steel with a final thickness of7.5 mm are the thickness of the original slab, the thickness of intermediate slab, and the rough rolling exit temperature from the specific hot rolling production line.

Low-frequency and broadband vibration energy harvester driven by mechanical impact based on layer-separated piezoelectric beam

Vibration energy harvesting is to transform the ambient mechanical energy to electricity. How to reduce the resonance frequency and improve the conversion efficiency is very important. In this paper, a layer-separated piezoelectric cantilever beam is proposed for the vibration energy harvester(VEH) for low-frequency and wide-bandwidth operation, which can transform the mechanical impact energy to electric energy. First,the electromechanical coupling equation is obtained by the Euler-Bernoulli beam theory.Based on the average method, the approximate analytical solution is derived and the voltage response is obtained. Furthermore, the physical prototype is fabricated, and the vibration experiment is conducted to validate the theoretical principle. The experimental results show that the maximum power of 0.445 μW of the layer-separated VEH is about3.11 times higher than that of the non-impact harvester when the excitation acceleration is 0.2 g. The operating frequency bandwidth can be widened by increasing the stiffness of the fundamental layer and decreasing the gap distance of the system. But the increasing of operating frequency bandwidth comes at the cost of reducing peak voltage. The theoretical simulation and the experimental results demonstrate good agreement which indicates that the proposed impact-driving VEH device has advantages for low-frequency and wide-bandwidth. The high performance provides great prospect to scavenge the vibration energy in environment.

Bioeffects of Low Energy Ion Beam Implantation:DNA Damage,Mutation and Gene Transter

Low-energy ion beam implantation （10 - 200 keV） has been proved to have a wide range of biological effects and is broadly used in the breeding of crops and micro-organisms.To understand its mechanisms better and facilitate its applications, the developments in the bioeffects of low energy ion beam implantation in the past twenty years are summarized in this paper.

Design of low-energy building and energy consumption analyses

In China,a new "Design standard for energy efficiency of residential buildings (for cold region)" was introduced in 2006. In this new standard,more high level insulation of the building envelope is required,yearly energy requirement for heating must be less than 55 kWh/(m2·a)(regarded as a low-energy house). The new attempt was carried out in the process of architecture design with an evaluation on energy consumption of the building. The design plan was brought forward and compared. PHPP software from German was applied to calculate energy consumption of the passive residential building. The optimum design planning was discussed and model of passive house suited to China's national conditions were attempted. The compactness,solar air collector and the window-wall ratio have essential influence on the energy consumption of buildings. The annual heat demands for the buildings with the window-wall ratio 0.35 and 0.50 are 48 kWh/(m2·a) and 46 kWh/(m2·a),respectively. The yearly auxiliary heat of building with the wall-mounted solar air collectors and the window-wall ratio 0.35 is just 4.8 kWh/(m2·a).

Preliminary Studies on Base Substitutions and Repair of DNA Mismatch Damage Stimulated by Low Energy N^+ Ion Beam Implantation in Escherichia coli

Ever since the low energy N+ ion beam has been accepted that the mutation effects of ionizing radiation are attributed mainly to direct or indirect damage to DNA. Evidences based on naked DNA irradiation in support of a mutation spectrum appears to be consistent, but direct proof of such results in vivo are limited. Using mutS, dam and/or dcm defective Eschericha coli imitator strains, an preliminary experimental system on induction of in vivo mutation spectra of low energy N+ ion beam has been established in this study. It was observed that the mutation rates of rifampicin resistance induced by N+ implantation were quite high, ranging from 9.2 x 10~8 to 4.9× 10~5 at the dosage of 5.2×1014 ions/cm2. Strains all had more than 90-fold higher mutation rate than its spontaneous mutation rate determined by this method. It reveals that base substitutions involve in induction of mutation of low energy nitrogen ion beam implantation. The mutation rates of mutator strains were nearly 500-fold (GM2929), 400-fold (GM5864) and 6-fold larger than that of AB1157. The GM2929 and GM5864 both lose the ability of repair DNA mismatch damage by virtue of both dam and dcm pathways defective (GM2929) or failing to assemble the repair complex (GM5864) respectively. It may explain the both strains had a similar higher mutation rate than GM124 did. It indicated that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N+ implantation. The further related research were also discussed.

High Energy and High Coercivity Sintered NdFeB Magnets by Low Oxygen Process

Using ball milling and single direction pressing, we can produce high performance NdFeB sintered magnets. The oxygen content of sintered magnets can be controlled under 1500xl0^-6 and the magnetic performance can be improved by using low oxygen processing. The high preformance NdFeB sintered magnets with Br=(1.4 ± 0.2)T, iHc>796 kA/m and (BH)max=(390± 16) kJ/m^3, have been batch produced.

The Dosimetric Characteristics and Potential Limitation in Clinical Application of a Low Energy Photon Intra-Operative Radiotherapy System

Purpose: To investigate the dosimetric characteristics of a low energy photon intra-operative radiotherapy (IORT) system and explore its potential limitation in clinical application. Methods: A special water phantom, a parallel-plate ionization chamber and an electrometer were used to measure the depth dose rate, isotropy of dose distribution in X/Y plane, dosimetry reproducibility of bare probe and spherical applicators of different size which were used in comparison with the system data. Results: The difference in depth dose rate between the measurement and system data for bare probe is -2.16% ± 1.36%, the range of the relative deviation for isotropy in the X/Y plane is between -1.9% and 2.1%. The difference in depth dose rate, transfer coefficient, isotropy in X/Y plane between the measurement and system data for the whole set of spherical applicators is -10.0% - 2.3%, -8.9% - 4.2% and -1.6% - 2.6%, respectively. Higher surface dose rate and steeper gradient depth dose are observed in smaller spherical applicators. The depth dose rate and isotropy for bare probe and spherical applicators have been shown good reproducibility. The uncertainty of measurement is associated with the positioning accuracy, energy response, noise current and correction function f’(R). Conclusions: Thorough commissioning of the low energy photon IORT system helps us better understand the dosimetry characteristics, verify the system data, obtain adequate data for clinical application and routine quality assurance. The steep gradient depth dose and limited treatment range may restrain its potential in clinical application.