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Precision and Efficiency of the Method of Moments Applied to the Functional Functions with Fold Points
Qingqiu Zhou,
Junjie Wang
Issue:
Volume 10, Issue 5, October 2022
Pages:
279-285
Received:
7 August 2022
Accepted:
1 September 2022
Published:
5 September 2022
DOI:
10.11648/j.sd.20221005.11
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Abstract: In the reliability theory, the moment method proposed by Zhao obtains the first fourth order moments of the structural function by the point estimation method based on Gauss-Emhart integral, assuming that the functional function satisfies a specific distribution or the approximate probability distribution function of the functional function is obtained by the Pearson system, so as to solve the reliability index and failure probability of the structure. For the elastic phase, the structural function is a smooth curve, and a large number of cases have proved that only 5-point estimation or 7-point estimation is required, and the moment method can achieve high accuracy, and the accuracy increases monotonically with the increase of the estimated number of points. In the case of structural elasto-plastic analysis, such as bridge ship impact analysis and structural static elasto-plastic analysis, the functional function will have folded points, and the accuracy and efficiency of the method of moments need to be studied. Comparing the calculation results of the method of moments and Monte-Carlo simulation, the accuracy of the method of moments does not increase monotonically with the increase of the estimated number of points in the case of the functional function with fold points, and when the number of estimated points is sufficient, generally 15-23, the calculation results of the method of moments are basically stable and have good accuracy. Under the same accuracy requirement, the calculation volume of the method of moments increases when the function function has fold points compared with the smooth function case, but the Monte-Carlo simulation still has higher calculation efficiency compared with the smooth function case.
Abstract: In the reliability theory, the moment method proposed by Zhao obtains the first fourth order moments of the structural function by the point estimation method based on Gauss-Emhart integral, assuming that the functional function satisfies a specific distribution or the approximate probability distribution function of the functional function is obta...
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Influence of Flow Channel Structure on Battery Thermal Management Performance
Yang Sun,
Vladislav Mitin,
Jintao Jin,
Kejun Zhu,
Xipo Lu
Issue:
Volume 10, Issue 5, October 2022
Pages:
286-291
Received:
9 August 2022
Accepted:
7 September 2022
Published:
8 September 2022
DOI:
10.11648/j.sd.20221005.12
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Abstract: Effective battery thermal management is crucial to the design of high performance and durable batteries for electric vehicles. In order to reduce the flow resistance of the traditional straight linear flow channel, the author proposed a divergent-shaped channel. In this paper, a battery thermal management model was established for the design of divergent flow channel by numerical simulation method. The momentum, mass and energy conservation equations of the coolant and the energy conservation equations of the cold plate and the battery were considered. In this work, the influence of the sub-channel outlet width on pressure drop and temperature difference is investigated. When the sub-channel outlet width increases from 3mm to 6mm, the pressure drop reduced by 41.76%, at the same time the battery temperature differential also decreased by 17%. In addition, it is found that the optimal sub-channel outlet width is 10 mm. In order to improve the performance of the divergent-shaped channel, a partition divergent-shaped channel design is proposed, and the effects of inlet vertical channel width Wfd and outlet vertical channel width Wbd are studied. Compared with Wbd, The effect of Wfd was more significant. With the increase of Wfd, both pressure drop and temperature difference decrease gradually. The research in this paper will contribute to the development of more efficient and energy saving battery thermal management system.
Abstract: Effective battery thermal management is crucial to the design of high performance and durable batteries for electric vehicles. In order to reduce the flow resistance of the traditional straight linear flow channel, the author proposed a divergent-shaped channel. In this paper, a battery thermal management model was established for the design of div...
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Improved Multilevel PWM Strategy Based on Control Carrier Freedom
Qiao He,
Zhao Ziqi,
Liu Ming
Issue:
Volume 10, Issue 5, October 2022
Pages:
292-299
Received:
30 August 2022
Accepted:
22 September 2022
Published:
28 September 2022
DOI:
10.11648/j.sd.20221005.13
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Abstract: Cascade multilevel inverte are widely concerned for it large number of levels, minimizes the of switching devices, large transmission power, and so on. However, the output waveform quality depends on the selection of pulse width modulation strategy. With the increase of the number of cascaded units and the output voltage level, it is of great significance to increase the utilization ratio of DC side voltage under carrier phase shift pulse width modulation (CPS-PWM) strategy and to improve the poor harmonic erformance in low-key system. Aiming at these two problems, this paper proposes an improved multilevel PWM modulation strategy based on the control carrier degree of freedom. The strategy according controls the combination of carrier degrees of freedom, based on the traditional CPS-PWM modulation strategy and combined with the carrier shape characteristics of APOD-PWM modulation strategy, the original triangular carrier is reconstructed to generate an improved carrier and applying to the modulation of multilevel inverter, which can resolve effectively the problems of poor harmonic performance and low DC voltage utilization rate of the output voltage when the modulation is low, in addition, it retains the advantage of the working stress of each switch tube is also the same and the power balance of each cascaded unit of the CPS-PWM strategy. In this paper, the principle and amplitude of output voltage of the improved carrier and CPS-PWM modulation strategy are compared and analyzed, and the strategy is verified by simulation and experiment.
Abstract: Cascade multilevel inverte are widely concerned for it large number of levels, minimizes the of switching devices, large transmission power, and so on. However, the output waveform quality depends on the selection of pulse width modulation strategy. With the increase of the number of cascaded units and the output voltage level, it is of great signi...
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Discussion on the Construction of Urban Transportation Brain in New Era
Ma Xiaoyi,
Xu Liang,
Jiang Xuefeng
Issue:
Volume 10, Issue 5, October 2022
Pages:
300-305
Received:
8 September 2022
Accepted:
5 October 2022
Published:
11 October 2022
DOI:
10.11648/j.sd.20221005.14
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Abstract: The transformation of the economy from high-speed to high-quality development in the new era urgently requires more accurate transportation support and guidance. The construction of the urban transportation brain will help achieve the goal of "more accurate". Reviewing the emergence of the concept of "urban transportation brain", analyzing the advantages and disadvantages of government-led transportation models and enterprise-led urban transportation brains, and establishing the urgency and necessity of government-led construction of transportation traffic brains. It expounds the new requirements for transportation in the new era from three dimensions: responding to the reform of spatial planning of national territory, responding to regional coordinated development, and supporting the construction of China’s Strength in Transportation. The superiority of the government-led construction is further demonstrated by clarifying the positioning of the urban transportation brain function with clear coordination and guidance. The application scenarios of the transportation brain in national territory space, regional planning and China’s Strength in Transportation are refined, and implementation suggestions are put forward from three aspects: improving top-level design, strengthening linkage feedback and promoting policy norms. Finally, it is proposed that the enhancement of the feasibility of the top-level design requires more cities to join in the construction of urban transportation brains.
Abstract: The transformation of the economy from high-speed to high-quality development in the new era urgently requires more accurate transportation support and guidance. The construction of the urban transportation brain will help achieve the goal of "more accurate". Reviewing the emergence of the concept of "urban transportation brain", analyzing the adva...
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EPC Procurement Model in China to Reduce the Project Direct Cost
Lan Zhang,
Hao Hu,
Jian Chen,
Aiguo Huang
Issue:
Volume 10, Issue 5, October 2022
Pages:
306-313
Received:
7 September 2022
Accepted:
29 September 2022
Published:
11 October 2022
DOI:
10.11648/j.sd.20221005.15
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Abstract: Low profit margin is a common issue for construction companies globally, especially for Chinese contractors. In this study, we aim to reduce the project direct cost using the procurement model to enable the contractors to increase their profit at the project level in China. The traditional procurement method used by Chinese contractors is to divide the project direct cost into several big packages, such as civil, structure, structural steel, curtain wall, mechanical, electrical, and plumbing, thus giving away the profit to the subcontractors. However, in North America, contractors use the trade packages and purchase major materials and facility equipment directly as per the specifications, and thus have more control over the project and markup of materials and equipment. In this study, we start with the supply chain model, analyze the western procurement practice, and propose an EPC procurement mode. The proposed model categorizes packages into five groups according to the different characteristics of the procured content, provides different contract templates, utilizes the appropriate contract, provides opportunity for negotiating with suppliers, and manages the interface carefully to reduce the project direct cost, thereby enabling the contractor to increase the profit margin to make the contractor more competitive in the market. The model was further presented and verified using a case study for Chinese contractors by utilizing the procurement model, so that the contractor can reduce the direct cost.
Abstract: Low profit margin is a common issue for construction companies globally, especially for Chinese contractors. In this study, we aim to reduce the project direct cost using the procurement model to enable the contractors to increase their profit at the project level in China. The traditional procurement method used by Chinese contractors is to divide...
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Research on Green Development Strategy of Urban Park Based on Pedestrian Simulation
Wei Gan,
Zongyu Hong,
Kaimin Liu
Issue:
Volume 10, Issue 5, October 2022
Pages:
314-322
Received:
15 September 2022
Accepted:
10 October 2022
Published:
17 October 2022
DOI:
10.11648/j.sd.20221005.16
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Abstract: With the rapid progress of urbanization, a large number of urban parks have been left idle and wasted because their spatial quality does not meet the needs of current users. Based on field research, this study uses pedestrian simulation methods to simulate the exploration of space by pedestrians in urban parks at the micro level over a period of time, which is equivalent to the activity trajectory of park visitors, to grasp the use of park space, to analyze the problems of existing solutions, and then to propose optimization strategies. The three main design strategies of road optimization to improve spatial accessibility, area expansion to improve node openness, and functional adaptation to improve environmental quality are used to optimize the design of the case park, and the simulation is conducted again after the optimization is completed to compare and analyze the simulation of pedestrians in the case park space before and after the optimization to verify the effectiveness of the optimization scheme. The results of the study prove that the pedestrian simulation method can be applied to the optimal design of urban park optimization: the introduction of pedestrian simulation method in the optimal design of urban park can make the design space layout more reasonable, improve the space utilization efficiency of urban park, and reduce the construction cost in order to achieve the purpose of green development.
Abstract: With the rapid progress of urbanization, a large number of urban parks have been left idle and wasted because their spatial quality does not meet the needs of current users. Based on field research, this study uses pedestrian simulation methods to simulate the exploration of space by pedestrians in urban parks at the micro level over a period of ti...
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Preparation and Property Study on Poly(vinyl alcohol) Aqueous Film
Issue:
Volume 10, Issue 5, October 2022
Pages:
323-327
Received:
1 September 2022
Accepted:
9 October 2022
Published:
17 October 2022
DOI:
10.11648/j.sd.20221005.17
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Abstract: With good water solubility and decomposition, poly(vinyl alcohol) (PVA) with low degree of polymerization used as non-fiber, has obvious advantages than commercial PVA and has a broad development prospect. However, the degree of polymerization of commercial PVA ranges from 300 to 2600 and it is hardly to get a smaller degree of polymerization by general aggregation methods. In this paper, low molecular weight of poly(vinyl acetate copolymerization acrylic acid) was prepared by utilizing chloroform as chain transfer agents and azodiisobutyronitrile (AIBN) as initiator by precipitation polymerization, and then corresponding PVA was obtained after alcoholysis. The molecular weight of poly(vinyl acetate copolymerization acrylic acid) was from 4020 to 4550 and the degree of polymerization of PVA was about 50 by analyzied by viscosity test and Gel permeation ghromatography (GPC). The structures and properties of PVA were also studied by Fourier Transform Infrared Spectroscopy (FTIR), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and water solubility test and the effect of acrylic acid on melting temperature, degree of crystallinity and water solubility were carefully studied. The results show that acrylic acid has little effect on the thermal stability of PVA.The degree of crystallinity of PVA decreases, water solubility increases, can rapidly dissolve in water at room.
Abstract: With good water solubility and decomposition, poly(vinyl alcohol) (PVA) with low degree of polymerization used as non-fiber, has obvious advantages than commercial PVA and has a broad development prospect. However, the degree of polymerization of commercial PVA ranges from 300 to 2600 and it is hardly to get a smaller degree of polymerization by ge...
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Practice of Life Safety Information Warning Management for Patients with Loss of Consciousness in Outpatients of General Hospital
Wang Danting,
Fan Yanmei,
Wang Lijuan,
Li Jie
Issue:
Volume 10, Issue 5, October 2022
Pages:
328-331
Received:
12 August 2022
Accepted:
17 October 2022
Published:
24 October 2022
DOI:
10.11648/j.sd.20221005.18
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Abstract: To explore the effect of life safety information warning management for patients with loss of consciousness in outpatient department of general hospital. The patients with loss of consciousness in outpatients of the Second Affiliated Hospital of Xi 'an Jiaotong University were given life safety information warning management along with routine medical care safety management. The PDCA cycle quality management model was used to develop a life safety warning management system, and centralized and standardized management was carried out for the patients with loss of consciousness in outpatients. Develop and apply the register of critically ill patients, implement the rescue system of critically ill patients, optimize the first aid process and feedback the effect., etc. The results showed that there were statistically significant differences in the incidence of adverse events in patients with loss of consciousness before and after the implementation of life safety information warning management (p=0.001). Warning management of life safety information for outpatients with loss of consciousness can improve the risk awareness of outpatient staff, enhance the first-aid level of outpatient staff, ensure the safety of life and property of patients, promote nurse-patient relationship, improve the comprehensive service quality of medical institutions, reduce the occurrence of medical disputes, and improve patient satisfaction.
Abstract: To explore the effect of life safety information warning management for patients with loss of consciousness in outpatient department of general hospital. The patients with loss of consciousness in outpatients of the Second Affiliated Hospital of Xi 'an Jiaotong University were given life safety information warning management along with routine medi...
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Research on Fault Location of Distribution Network with DG Based on HHO
Yan Xin,
Liu Ruichen,
Tu Naiwei,
Xing Jiaqi
Issue:
Volume 10, Issue 5, October 2022
Pages:
332-339
Received:
20 September 2022
Accepted:
18 October 2022
Published:
24 October 2022
DOI:
10.11648/j.sd.20221005.19
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Abstract: Power generation, transmission, transformation, distribution and use are several important links in the power system, of which the distribution link is the most important. Since the 18th National Congress of the CPC, with the acceleration of carbon peaking and carbon neutrality process, clean energy such as solar power generation, wind power generation and fuel cells has developed rapidly, and the energy utilization mode has become complex and diversified. The access of these distributed power sources has put forward higher requirements for the safe and stable operation of the power system. Therefore, the research on fault location has become an indispensable part of the research on the stability of distribution network. In order to enhance the accuracy and speed of fault location, a distributed power distribution network fault location method based on Harris Eagle algorithm was proposed. The specific process is: when a fault occurs in the power grid, FA (feeder automation) will first monitor the error message and upload it to FTU (feeder terminal unit), and FTU will interpret the error message according to HHO algorithm and accurately locate it to the fault section. However, the traditional HHO is not suitable for the discreteness problem, so it is first converted into a binary BHHO, based on this, new fault location coding mode, switching function and evaluation function suitable for binary system are constructed. BHHO is applied to the IEEE33 bus distribution network model with DG, and compared with GA and PSO under the conditions of single point fault, multi-point fault and information distortion fault The simulation results show that the accuracy and speed of BHHO are better than those of GA and PSO under various fault conditions. The results prove that HHO can better enhance the accuracy and stability of fault location in distribution network.
Abstract: Power generation, transmission, transformation, distribution and use are several important links in the power system, of which the distribution link is the most important. Since the 18th National Congress of the CPC, with the acceleration of carbon peaking and carbon neutrality process, clean energy such as solar power generation, wind power genera...
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Research on Rice Nitrogen Nutrition Diagnosis System Based on Deep Learning Model and Android
Qiang Yao,
Bin Lyu,
Chao Su,
Bo Li
Issue:
Volume 10, Issue 5, October 2022
Pages:
340-346
Received:
16 September 2022
Accepted:
20 October 2022
Published:
24 October 2022
DOI:
10.11648/j.sd.20221005.20
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Abstract: Nitrogen nutrition diagnosis is one of the key technologies to achieve high quality and high yield in rice. It is time-consuming and laborious to use traditional diagnosis methods of rice nitrogen nutrition. Rapid and intelligent diagnosis of rice nitrogen nutrition can be realized by using smart phones and image recognition technology. In order to use mobile equipment to carry out nitrogen nutrition diagnosis in rice anytime and anywhere, and providing suggestions and prescriptions for fertilization management, by migrating the deep learning model to the Android environment, the rice nitrogen nutrition diagnosis system based on Android has been developed according to the established deep learning model of rice nitrogen nutrition recognition based on TensorFlow. The diagnosis results of the developed system have been verified and analyzed using the collected image data. At first, comparative analysis was conducted on various nitrogen nutrition diagnosis methods for rice, and then, image processing technology, image recognition technology, the configuration of development environment, system design and implementation, verification and analysis of diagnosis results have been emphatically introduced. The techniques and development methods used in the experiments are feasible and reproducible. The results of rice nitrogen nutrition recognition using the Android-based rice nitrogen nutrition diagnosis system were the same as the validation results of the original model.
Abstract: Nitrogen nutrition diagnosis is one of the key technologies to achieve high quality and high yield in rice. It is time-consuming and laborious to use traditional diagnosis methods of rice nitrogen nutrition. Rapid and intelligent diagnosis of rice nitrogen nutrition can be realized by using smart phones and image recognition technology. In order to...
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Study on the Spatial Pattern and Influencing Factors of Life Elements in Jiumiao Site of Chang'an City in Han Dynasty Based on POI Data
Issue:
Volume 10, Issue 5, October 2022
Pages:
347-360
Received:
20 September 2022
Accepted:
24 October 2022
Published:
27 October 2022
DOI:
10.11648/j.sd.20221005.21
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Abstract: The overlapping of industrial remains and historical relics in the Nine temple ritual building site of Chang 'an City of Han Dynasty restricts the renewal and development of the area, and further affects the improvement of the quality of life of the native residents. Research based on the POI data with other multi-source data, using the kernel density estimation, and standard deviation ellipse, bivariate spatial autocorrelation (Moran's I) and methods of geographical detector, at sites in the five essentials ("food, medical, shopping, entertainment", five elements) of the spatial pattern characteristics and influence factors of life elements layout optimization strategy is put forward. The results showed that: (1) all life elements in the site generally formed a spatial pattern of "linear penetration, branching extension, dense in the south and sparse in the north", showing a "northeast to southwest" trend distribution; (2) There is an obvious regional gap in the spatial aggregation level of various life factors, forming an "isolated island" gathering area, and the spatial matching degree is obviously different, and the gathering area of travel factors has a spatial dislocation. Is the cause of the above characteristics: Controlled by a variety of restrictive conditions of undeveloped site area, in the process of its slow development density factors affect the traffic network, gradually formed section of oriented uniaxial aggregation structure, single elements of the structure pattern has obvious exclusivity makes relatively weak in the influence of other factors, is not conducive to more reasonable location choice factors of diversified life
Abstract: The overlapping of industrial remains and historical relics in the Nine temple ritual building site of Chang 'an City of Han Dynasty restricts the renewal and development of the area, and further affects the improvement of the quality of life of the native residents. Research based on the POI data with other multi-source data, using the kernel dens...
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Software Excel Assists College Mathematics Teaching
Liang Haibin,
Ling Haiqing
Issue:
Volume 10, Issue 5, October 2022
Pages:
361-365
Received:
22 September 2022
Accepted:
20 October 2022
Published:
27 October 2022
DOI:
10.11648/j.sd.20221005.22
Downloads:
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Abstract: The cultivation of mathematics application ability is an important purpose in college mathematics teaching, and it is also a weak link. The significance of introducing Excel software in college mathematics courses is to improve students' learning efficiency and interest, and to cultivate students' ability to use mathematical knowledge to solve practical problems. Compared with other mathematical software, Excel has great simplicity. Using the calculation, drawing, built-in functions, and statistical analysis functions of EXCEL software, explore a teaching method that is beneficial to students' learning of mathematics courses, and help students to understand and master the theoretical basis and methods of calculus, probability and statistics, and linear algebra skill. Through the comparative analysis of the scores of the control group who introduced the software Excel, as well as the effect analysis of the improvement of students' mathematical ability and computer ability, it is found that the introduction of the software Excel in the university mathematics classroom is conducive to improving the students' big data processing ability, mathematical modeling ability and Apply innovation capabilities. At the same time, the introduction of the software Excel in the mathematics classroom has also improved the teachers' software office ability.
Abstract: The cultivation of mathematics application ability is an important purpose in college mathematics teaching, and it is also a weak link. The significance of introducing Excel software in college mathematics courses is to improve students' learning efficiency and interest, and to cultivate students' ability to use mathematical knowledge to solve prac...
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Design of Question Answering System in Substation Fault Field Based on Knowledge Graph
He Jun,
Wu Sheng Ke,
Rao Fang Xi,
Zhong Ke Jia,
Liu Peng Zheng,
Sun Jian Ming
Issue:
Volume 10, Issue 5, October 2022
Pages:
366-373
Received:
26 September 2022
Accepted:
27 October 2022
Published:
29 October 2022
DOI:
10.11648/j.sd.20221005.23
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Abstract: The operation and maintenance of substation equipment is of great significance to ensure the safety and stability of the power grid. In order to summarize the historical operation and maintenance experience of substation equipment and facilitate the management personnel to uniformly manage and accurately query the historical data of substation faults, this paper constructs an intelligent question and answer system for substation faults based on the knowledge map. At present, the research on knowledge atlas in power field mainly focuses on the construction and visualization of knowledge atlas. This paper combines natural language processing, deep learning, knowledge atlas, graph database and other knowledge with power. Firstly, the substation fault data is cleaned and extracted, and the substation fault knowledge map is constructed; Secondly, based on Bert+TextCNN algorithm, the intention recognition function of questions is realized; Thirdly, based on BILSTM-CRF algorithm, the named entity recognition function of questions is realized. Finally, combined with Flask deployment model, the API interface is released, and the substation fault question answering system is built through the establishment of WeChat automatic question answering robot. The experimental results show that the accuracy of the system reaches 96%. Finally, a complete question answering system for substation fault is formed, and accurate, fast and intelligent knowledge question answering service is realized.
Abstract: The operation and maintenance of substation equipment is of great significance to ensure the safety and stability of the power grid. In order to summarize the historical operation and maintenance experience of substation equipment and facilitate the management personnel to uniformly manage and accurately query the historical data of substation faul...
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