Most existing handover decision system （HDS） designs are monolithic, resulting in high computational cost and unbalance of overall network. A novel modular handover algorithm with a comprehensive load index for the ...Most existing handover decision system （HDS） designs are monolithic, resulting in high computational cost and unbalance of overall network. A novel modular handover algorithm with a comprehensive load index for the 5th generation （5G） heterogeneous networks （HetNets） is proposed. In this paper, the handover parameters, serving as the basis for handover, are classified into network＇s quality of service （QoS） module, user preference （UP） module and degree of satisfaction （DS） module according to the new modular HDS design. To optimize switching process, the comprehensive network load index is deduced by using triangle module fusion operator. With respect to the existing handover algorithm, the simulation results indicate that the proposed algorithm can reduce the handover frequency and maintain user satisfaction at a higher level. Meanwhile, due to its block calculation, it can bring about 1.4 s execution time improvement.展开更多
AIM:To determine the glycemic index(GI),glycemic load(GL)and insulinemic index(Ⅱ)of five starchy foods that are commonly used in Chinese diets.METHODS:Ten healthy subjects aged between 20-30 years were recruited.Each...AIM:To determine the glycemic index(GI),glycemic load(GL)and insulinemic index(Ⅱ)of five starchy foods that are commonly used in Chinese diets.METHODS:Ten healthy subjects aged between 20-30 years were recruited.Each subject was asked to consume 50 g of available carbohydrate portions of test foods and reference food.Finger capillary blood samples were collected at the start of eating and 15,30,45,60,90 and 120 min after consumption.The GI and Ⅱ of foods were calculated from the ratio of incremental area under the glucose/insulin response curves of test and reference foods.The GL for each test food was determined from its GI value and carbohydrate content.RESULTS:The results showed that brown rice elicited the highest postprandial glucose and insulin responses,followed by taro,adlay,yam and mung bean noodles,which produced the lowest.Among the five starchy foods,brown rice evoked the highest GI and GL at 82±0.2 and 18±0.2,followed by taro(69±0.4,12±0.2),adlay(55±0.4,10±0.2),yam(52±0.3,9±0.0)and mung bean noodles(28±0.5,7±0.2),respectively.The Ⅱ values of the test foods corresponded with GI values.Similarly,brown rice gave the highest Ⅱ at 81±0.1,followed by taro(73±0.3),adlay(67±0.3),yam(64±0.5) and mung bean noodles(38±0.3).All five starchy foods had lower GI,GL and Ⅱ than reference bread(P<0.05).CONCLUSION:The GI,GL and Ⅱ values of starchy foods provide important information for the public to manage their diet and could be useful for the prevention of lifestyle-related diseases such as diabetes mellitus.展开更多
AIM:To determine the glycemic index(GI)and glycemic load(GL)values of Chinese traditional foods in Hong Kong.METHODS:Fifteen healthy subjects(8 males and 7 females)volunteered to consume either glucose or one of 23 te...AIM:To determine the glycemic index(GI)and glycemic load(GL)values of Chinese traditional foods in Hong Kong.METHODS:Fifteen healthy subjects(8 males and 7 females)volunteered to consume either glucose or one of 23 test foods after 10-14 h overnight fast.The blood glucose concentrations were analyzed immediately before,15,30,45,60,90 and 120 min after food consumption using capillary blood samples.The GI value of each test food was calculated by expressing the incremental area under the blood glucose response curve(IAUC)value for the test food as a percentage of each subject's average IAUC value for the glucose.The GL value of each test food was calculated as the GI value of the food multiplied by the amount of the available carbohydrate in a usual portion size,divided by 100.RESULTS:Among all the 23 Chinese traditional foods tested,6 of them belonged to low GI foods(Tuna Fish Bun,Egg Tart,Green Bean Dessert,Chinese Herbal Jelly,Fried Rice Vermicelli in Singapore-style,and Spring Roll),10 of them belonged to moderate GI foods(Baked Barbecued Pork Puff,Fried Fritter,"Mai-Lai"Cake,"Pineapple"Bun,Fried Rice Noodles with Sliced Beef,Barbecue Pork Bun,Moon Cakes,Glutinous Rice Ball,Instant Sweet Milky Bun,and Salted Meat Rice Dumpling),the others belonged to high GI foods(Fried Rice in Yangzhou-Style,Sticky Rice Wrapped in Lotus Leaf,Steamed Glutinous Rice Roll,Jam and Peanut Butter Toast,Plain Steamed Vermicelli Roll,Red Bean Dessert,and Frozen Sweet Milky Bun).CONCLUSION:The GI and GL values for these Chinese traditional foods will provide some valuable information to both researchers and public on their food preference.展开更多
In this paper, three rock types including Sandstone, Mudstone, and Crystalline Gypsum were part of a laboratory study conducted to develop a dataset for predicting the unconfined compressive strength of UAE intact sed...In this paper, three rock types including Sandstone, Mudstone, and Crystalline Gypsum were part of a laboratory study conducted to develop a dataset for predicting the unconfined compressive strength of UAE intact sedimentary rock specimens. Four hundred nineteen rock samples from various areas along the coastal region of the UAE were collected and tested for the development of this dataset and evaluation of models. From the statistical analysis of the data, regression equations were established among rock parameters and correlations were expressed and compared by the ones proposed in literature.展开更多
Food intake has a great influence on blood glucose in patients with diabetes. This study was to determine the glycemic index（GI） and glycemic load（GL） of a particular pomelo named Majia pomelo and its effects on p...Food intake has a great influence on blood glucose in patients with diabetes. This study was to determine the glycemic index（GI） and glycemic load（GL） of a particular pomelo named Majia pomelo and its effects on postprandial glucose（PPG） in patients with type 2 diabetes（T2D）. Twenty healthy subjects and 20 T2D patients（controlled on lifestyle measures and/or metformin） were tested on 2 separate days with 50 g of glucose and 50 g equivalent of carbohydrates from Majia pomelo for GI measurement. To test effects of Majia pomelo on PPG, 19 hospitalized T2D patients（controlled on insulin therapy） were selected for a 9-day study. The dose of insulin for each patient was adjusted on the first 3 days. A total of 100 g Majia pomelo was consumed per meal in the last 3 tested days. Blood glucose was measured to evaluate the glycemic excursions. The GIs for Majia pomelo in healthy individuals and T2D patients were 78.34±1.88 and 72.15±1.95 respectively. The value of GL was as low as 4.23 in diabetic patients with serving size of 100 g pomelo, indicting Majia pomelo as a high GI but low GL fruit. Consumption of Majia pomelo in hospitalized T2D patients did not cause significant glucose fluctuation. It was concluded that high GI pomelo can serve as a low GL fruit if it is consumed with a limited daily amount and thus can be supplied to diabetic patients. These results may mean more varieties of food choices for T2D patients.展开更多
This paper proposes a new approach for suitable load buses identification via stability index tracing in performing corrective load shedding. The proposed identification technique is called the Fast Voltage Stability ...This paper proposes a new approach for suitable load buses identification via stability index tracing in performing corrective load shedding. The proposed identification technique is called the Fast Voltage Stability Index Load Tracing (FVSI-LT). By implementing a power tracing algorithm, a group of major contributors on the stress experienced by a power system is able to be precisely identified by a system operator (SO) based on the traced values of FVSI. To be precise, the traced FVSI via FVSI-LT can be used to form a ranking list indicating the priority of buses committed for shedding purpose. After designing a Fuzzy Inference System (FIS) for deciding the allowable load powers to be shed and performing experiment on IEEE 57-Bus reliability test system (RTS), it is revealed that the ranking list provided by FVSI-LT results to the most consistent improvement in terms of voltage stability and losses minimization.展开更多
The limitations of several existing classical rock damage models were critically appraised. Thereafter, a description of a new model to estimate the response of rock was provided. The results of an investigation lead ...The limitations of several existing classical rock damage models were critically appraised. Thereafter, a description of a new model to estimate the response of rock was provided. The results of an investigation lead to the development and confirmation of a new index parabola damage model. The new model is divided into two parts, fictitious damage and real damage and bordered by the critical damage point. In fictitious damage, the damage variable follows the index distribution, while in the real damage a parabolic distribution is used. Thus, the so called index parabola damage model is derived. The proposed damage model is applied to simulate the damage procedure of marble under uni axial loading. The results of the tests show that the proposed model is in excellent agreement with experimental data, in particular the nonlinear characteristic of rock deformation is adequately represented. [展开更多
5G基站、分布式光伏(distributed photovoltaic,DPV)等分布式资源大规模参与配电网经济与电能质量等多目标优化调度,致使配电网调控模型决策变量复杂、求解时间慢等问题凸显。为此,提出一种考虑5G基站调控潜力和多资源协同的配电网分层...5G基站、分布式光伏(distributed photovoltaic,DPV)等分布式资源大规模参与配电网经济与电能质量等多目标优化调度,致使配电网调控模型决策变量复杂、求解时间慢等问题凸显。为此,提出一种考虑5G基站调控潜力和多资源协同的配电网分层分区优化方法。首先,考虑5G基站通信流量波动特性,建立计及闲置荷电状态(state of charge,SOC)约束的5G基站调控潜力模型。基于此,再建立配电网分层分区优化模型。上层以配电网综合效益最优为目标进行集中式调度,从而确定配电网分组投切电容器组、静止无功发生器等自身资源的动作方案。下层为分区调度,结合电压-功率灵敏度和考虑5G基站通信负荷的源荷不匹配度指标进行配电网物理分区,建立面向5G基站闲置SOC和DPV剩余容量的配电网分区协调优化模型,并采用二阶锥规划和同步型交替方向乘子法相结合的混合算法进行求解。最后,以改进的IEEE33节点配电网为算例,分析验证了所提方法的有效性。结果表明,所提方法能够提高配电网调控模型的求解能力,并提升配电网经济性和电压质量。展开更多
Subjective scales have different kinds of applicability in diverse fields.This study intends to implement a quantitative approach to determine the applicability of subjective scales in manual as-sembly work and evalua...Subjective scales have different kinds of applicability in diverse fields.This study intends to implement a quantitative approach to determine the applicability of subjective scales in manual as-sembly work and evaluate the cognitive load of assembly workers.A multi-scale research paradigm based on subjective evaluation method is proposed.Three typical task stages are extracted from the process of assembly work.The National Aeronautics and Space Administration Task Load Index(NASA-TLX)scale,PAAS scale and Workload Profile Index Ratings(WP)scale are selected for the design of 3×3 multi-factor mixed experiment.The power spectrum density(PSD)characteris-tics of electroencephalogram(EEG)are utilized to identify the difficulty levels of the three task sta-ges.The relevant indicators of scale applicability are assessed.The results show that in terms of sensitivity,NASA-TLX scale reaches the highest sensitivity(F=999.137,P=0<0.05).In terms of validity,NASA-TLX scale possesses the best concurrent validity(P=0.0255<0.05).In terms of diagnosticity,NASA-TLX scale based on 6 dimensions takes on the best diagnostic performance.In terms of subject acceptability,WP scale performs the worst.According to the analytic hierarchy process(AHP)model,the applicability scores of NASA-TLX scale,PAAS scale and WP scale are determined as 3,2.55 and 1.6714,respectively.Therefore,NASA-TLX scale is regarded as the most suitable subjective evaluation questionnaire for assembly workers,which is also an effective quantitative evaluation method for the cognitive load of assembly workers.展开更多
The heavy metal contamination status of Bight of Bonny sea bed sediment w<span>as investigated. Sediment samples were collected from eleven locations grouped into three stations. The samples were analyzed to det...The heavy metal contamination status of Bight of Bonny sea bed sediment w<span>as investigated. Sediment samples were collected from eleven locations grouped into three stations. The samples were analyzed to determine the heavy met</span><span>als (Fe, Pb, Ni, Zn, Mn, Co, Cd, Cu, Cr) concentration using atomic absorption spectrophotometer. Index model analyses, such as geo-accumulation</span> index (I-geo), Enrichment factor (EF), and Pollution load index (PLI) were used for pollution assessment of sea bed sediment. The most predominant heavy metals in the upstream sediment were Fe;13.57 ± 1.838 mg/kg, cobalt;7.987 ± 3.550 mg/kg, and Ni;1.020 ± 0.802 mg/kg, midstream sediment were Fe;8.554 ± 3.010 mg/kg, Co;8.520 ± 4.00 mg/kg, and Ni;1.140 ± 0.879 mg/kg, while the downstream sediment result had Fe;11.12 ± 3.825 mg/kg, Co;7.275 ± 1.700 mg/kg, and Cd;1.025 ± 0.159 /kg. The I-geo results indicate that Cu, Mn, Pb, Cr, Fe, Zn, Ni, and Co were in their background concentrations while Cd had I-geo</span><span style="font-family:""> </span><span style="font-family:"">></span><span style="font-family:""> </span><span style="font-family:"">3 which implies a moderately or heavily polluted env<span>ironment. The EF indicates metal enrichment from anthropogenic sour</span>ces fo<span>r Co, Ni, Pb, Cd, Cu, and Cr while Fe and Mn predicate biogenic origin. The PLI of the heavy metals in the three sample stations of sea bed sediment was found to be generally low (<1). The Enrichment Factor and geo-ac</span>cumulation index strongly suggest the Bight of Bonny sea bed sediment contamination by Cd from anthropogenic sources.展开更多
The changing patterns of watersheds in a landscape, driven by human activities, play an important role in non-point source pollution processes. This paper aims to improve the location-weighted landscape contrast index...The changing patterns of watersheds in a landscape, driven by human activities, play an important role in non-point source pollution processes. This paper aims to improve the location-weighted landscape contrast index using remote sensing and GIS technology to account for the effects of scale and ecological processes. The hydrological response unit(HRU) with a single land use and soil type was used as the smallest unit. The relationship between the landscape index and typical ecological processes was established by describing the influence of the landscape pattern on non-point source pollution. To verify the research method, this paper used the Yanshi River basin as a study area. The results showed that the relative intensity of non-point source pollution in different regions of the watershed and the location-weighted landscape contrast index based on the minimum HRU can qualitatively reflect the risk of regional nutrient loss.展开更多
The study of the ecological system (ES) reaction to anthropogenous loading (AL) has been aimed at developing the remote sensing method for quantitative mapping of AL on ES. The analysis of the problem has shown that t...The study of the ecological system (ES) reaction to anthropogenous loading (AL) has been aimed at developing the remote sensing method for quantitative mapping of AL on ES. The analysis of the problem has shown that the main approach for its solution is to assess the amount of entropy induced in ES by AL. The general formalism has been dis-cussed and the thermodynamic index of ES health disturbance (TIEHD- ) has been deduced from the conservation law as a portion of solar exergy spent by ES on the parrying entropy formed in ES due to AL with respect to the total amount of exergy of solar irradiations absorbed by ES. The technique of remote mapping of TIEHD has been developed. The maps of TIEHD and the normalized differential vegetation index (NDVI)- have been compiled on the basis of NOAA and EOS satellite data. The qualitative and quantitative analysis exhibited the best sensitivity of TIEHD to AL on ES in respect to NDVI.展开更多
The expansion planning and operation of all three sectors, generation, transmission and distribution, of power system essentially require load forecasting. Weather conditions have significant impacts on forecasted loa...The expansion planning and operation of all three sectors, generation, transmission and distribution, of power system essentially require load forecasting. Weather conditions have significant impacts on forecasted load, especially short-term and mid-term. A momentous portion of the electrical energy is consumed, especially in cold or hot countries, to mitigate the impact of weather on the daily life of human society. Usually, weather dependent component of load is identified by fitting appropriate non-linear curve to the scatter plot of weather-load model. This technique some times shows lower correlation with weather variables. This paper proposes a new methodology to identify the weather sensitive component of electrical load using empirical mode decomposition (EMD) technique. The proposed methodology is applied to the daily peak load of Dhaka zone of Bangladesh Power System (BPS) of the year 2012. A detailed numerical process to evaluate the weather sensitive portion of the load is also presented. The proposed methodology is validated through statistical error evaluation process. Finally the salient features of the results are discussed.展开更多
Harmonic content of the voltage source inverters is important and must be in the allowed ranges. Different method are proposed to decrease the Total Harmonic Distortion (THD) and caused to be sinusoidal the output vol...Harmonic content of the voltage source inverters is important and must be in the allowed ranges. Different method are proposed to decrease the Total Harmonic Distortion (THD) and caused to be sinusoidal the output voltage of inverters. One of these methods is using multilevel structure. In this structure many important parameters which are effective on voltage source inverter operation that among them we can mention to modulation index (MI). Variation of modulation index can change the THD. One of the harmonic reduction methods is using multilevel structure. In this paper, a sample 5-level SHE-PWM voltage source inverter is presented and all equation and choosing switching angles for elimination desired harmonics from different order. To investigate the effective parameters on the inverter operation, a typical 5-level inverter is simulated in PSPICE software. The simulation has been done for different values of modulation and its effect on the inverter operation is evaluated.展开更多
基金supported by the Program for Innovation Team Building at Institutions of High Education in Chongqing (KJTD201312)the Hi-Tech Research and Development Program of China (2015AA01A705,2014AA01A706)
文摘Most existing handover decision system （HDS） designs are monolithic, resulting in high computational cost and unbalance of overall network. A novel modular handover algorithm with a comprehensive load index for the 5th generation （5G） heterogeneous networks （HetNets） is proposed. In this paper, the handover parameters, serving as the basis for handover, are classified into network＇s quality of service （QoS） module, user preference （UP） module and degree of satisfaction （DS） module according to the new modular HDS design. To optimize switching process, the comprehensive network load index is deduced by using triangle module fusion operator. With respect to the existing handover algorithm, the simulation results indicate that the proposed algorithm can reduce the handover frequency and maintain user satisfaction at a higher level. Meanwhile, due to its block calculation, it can bring about 1.4 s execution time improvement.
文摘AIM:To determine the glycemic index(GI),glycemic load(GL)and insulinemic index(Ⅱ)of five starchy foods that are commonly used in Chinese diets.METHODS:Ten healthy subjects aged between 20-30 years were recruited.Each subject was asked to consume 50 g of available carbohydrate portions of test foods and reference food.Finger capillary blood samples were collected at the start of eating and 15,30,45,60,90 and 120 min after consumption.The GI and Ⅱ of foods were calculated from the ratio of incremental area under the glucose/insulin response curves of test and reference foods.The GL for each test food was determined from its GI value and carbohydrate content.RESULTS:The results showed that brown rice elicited the highest postprandial glucose and insulin responses,followed by taro,adlay,yam and mung bean noodles,which produced the lowest.Among the five starchy foods,brown rice evoked the highest GI and GL at 82±0.2 and 18±0.2,followed by taro(69±0.4,12±0.2),adlay(55±0.4,10±0.2),yam(52±0.3,9±0.0)and mung bean noodles(28±0.5,7±0.2),respectively.The Ⅱ values of the test foods corresponded with GI values.Similarly,brown rice gave the highest Ⅱ at 81±0.1,followed by taro(73±0.3),adlay(67±0.3),yam(64±0.5) and mung bean noodles(38±0.3).All five starchy foods had lower GI,GL and Ⅱ than reference bread(P<0.05).CONCLUSION:The GI,GL and Ⅱ values of starchy foods provide important information for the public to manage their diet and could be useful for the prevention of lifestyle-related diseases such as diabetes mellitus.
基金Supported by General Research Fund from Research Grants Committee of The Government of the Hong Kong SAR,China, No.4440178
文摘AIM:To determine the glycemic index(GI)and glycemic load(GL)values of Chinese traditional foods in Hong Kong.METHODS:Fifteen healthy subjects(8 males and 7 females)volunteered to consume either glucose or one of 23 test foods after 10-14 h overnight fast.The blood glucose concentrations were analyzed immediately before,15,30,45,60,90 and 120 min after food consumption using capillary blood samples.The GI value of each test food was calculated by expressing the incremental area under the blood glucose response curve(IAUC)value for the test food as a percentage of each subject's average IAUC value for the glucose.The GL value of each test food was calculated as the GI value of the food multiplied by the amount of the available carbohydrate in a usual portion size,divided by 100.RESULTS:Among all the 23 Chinese traditional foods tested,6 of them belonged to low GI foods(Tuna Fish Bun,Egg Tart,Green Bean Dessert,Chinese Herbal Jelly,Fried Rice Vermicelli in Singapore-style,and Spring Roll),10 of them belonged to moderate GI foods(Baked Barbecued Pork Puff,Fried Fritter,"Mai-Lai"Cake,"Pineapple"Bun,Fried Rice Noodles with Sliced Beef,Barbecue Pork Bun,Moon Cakes,Glutinous Rice Ball,Instant Sweet Milky Bun,and Salted Meat Rice Dumpling),the others belonged to high GI foods(Fried Rice in Yangzhou-Style,Sticky Rice Wrapped in Lotus Leaf,Steamed Glutinous Rice Roll,Jam and Peanut Butter Toast,Plain Steamed Vermicelli Roll,Red Bean Dessert,and Frozen Sweet Milky Bun).CONCLUSION:The GI and GL values for these Chinese traditional foods will provide some valuable information to both researchers and public on their food preference.
文摘In this paper, three rock types including Sandstone, Mudstone, and Crystalline Gypsum were part of a laboratory study conducted to develop a dataset for predicting the unconfined compressive strength of UAE intact sedimentary rock specimens. Four hundred nineteen rock samples from various areas along the coastal region of the UAE were collected and tested for the development of this dataset and evaluation of models. From the statistical analysis of the data, regression equations were established among rock parameters and correlations were expressed and compared by the ones proposed in literature.
基金supported by grants from National Natural Science Foundation of China(No.81570740 and No.81100581)the Ministry of Science and Technology of China(No.2011CB100600)+3 种基金the Science and Technology Projects of Wuhan(No.201060938360-04 from the Wuhan Science and Technology Bureau)China International Medical Foundation(CIMF)--Novo Nordisk China Diabetes Yingcai Funding(No.2014)CIMF-Novo Nordisk China β Academy Funding(No.20110059)the Fundamental Research Funds for the Central Universities(No.0118540208)
文摘Food intake has a great influence on blood glucose in patients with diabetes. This study was to determine the glycemic index（GI） and glycemic load（GL） of a particular pomelo named Majia pomelo and its effects on postprandial glucose（PPG） in patients with type 2 diabetes（T2D）. Twenty healthy subjects and 20 T2D patients（controlled on lifestyle measures and/or metformin） were tested on 2 separate days with 50 g of glucose and 50 g equivalent of carbohydrates from Majia pomelo for GI measurement. To test effects of Majia pomelo on PPG, 19 hospitalized T2D patients（controlled on insulin therapy） were selected for a 9-day study. The dose of insulin for each patient was adjusted on the first 3 days. A total of 100 g Majia pomelo was consumed per meal in the last 3 tested days. Blood glucose was measured to evaluate the glycemic excursions. The GIs for Majia pomelo in healthy individuals and T2D patients were 78.34±1.88 and 72.15±1.95 respectively. The value of GL was as low as 4.23 in diabetic patients with serving size of 100 g pomelo, indicting Majia pomelo as a high GI but low GL fruit. Consumption of Majia pomelo in hospitalized T2D patients did not cause significant glucose fluctuation. It was concluded that high GI pomelo can serve as a low GL fruit if it is consumed with a limited daily amount and thus can be supplied to diabetic patients. These results may mean more varieties of food choices for T2D patients.
文摘This paper proposes a new approach for suitable load buses identification via stability index tracing in performing corrective load shedding. The proposed identification technique is called the Fast Voltage Stability Index Load Tracing (FVSI-LT). By implementing a power tracing algorithm, a group of major contributors on the stress experienced by a power system is able to be precisely identified by a system operator (SO) based on the traced values of FVSI. To be precise, the traced FVSI via FVSI-LT can be used to form a ranking list indicating the priority of buses committed for shedding purpose. After designing a Fuzzy Inference System (FIS) for deciding the allowable load powers to be shed and performing experiment on IEEE 57-Bus reliability test system (RTS), it is revealed that the ranking list provided by FVSI-LT results to the most consistent improvement in terms of voltage stability and losses minimization.
文摘The limitations of several existing classical rock damage models were critically appraised. Thereafter, a description of a new model to estimate the response of rock was provided. The results of an investigation lead to the development and confirmation of a new index parabola damage model. The new model is divided into two parts, fictitious damage and real damage and bordered by the critical damage point. In fictitious damage, the damage variable follows the index distribution, while in the real damage a parabolic distribution is used. Thus, the so called index parabola damage model is derived. The proposed damage model is applied to simulate the damage procedure of marble under uni axial loading. The results of the tests show that the proposed model is in excellent agreement with experimental data, in particular the nonlinear characteristic of rock deformation is adequately represented. [
文摘5G基站、分布式光伏(distributed photovoltaic,DPV)等分布式资源大规模参与配电网经济与电能质量等多目标优化调度,致使配电网调控模型决策变量复杂、求解时间慢等问题凸显。为此,提出一种考虑5G基站调控潜力和多资源协同的配电网分层分区优化方法。首先,考虑5G基站通信流量波动特性,建立计及闲置荷电状态(state of charge,SOC)约束的5G基站调控潜力模型。基于此,再建立配电网分层分区优化模型。上层以配电网综合效益最优为目标进行集中式调度,从而确定配电网分组投切电容器组、静止无功发生器等自身资源的动作方案。下层为分区调度,结合电压-功率灵敏度和考虑5G基站通信负荷的源荷不匹配度指标进行配电网物理分区,建立面向5G基站闲置SOC和DPV剩余容量的配电网分区协调优化模型,并采用二阶锥规划和同步型交替方向乘子法相结合的混合算法进行求解。最后,以改进的IEEE33节点配电网为算例,分析验证了所提方法的有效性。结果表明,所提方法能够提高配电网调控模型的求解能力,并提升配电网经济性和电压质量。
基金the National Natural Science Foundation of China(No.51775325)the Joint Funds of the National Natural Science Foundation of China(No.U21A20121)+1 种基金the Key Research and Development Program of Ningbo(No.2023Z218)the Young Eastern Scholars Program of Shanghai(No.QD2016033).
文摘Subjective scales have different kinds of applicability in diverse fields.This study intends to implement a quantitative approach to determine the applicability of subjective scales in manual as-sembly work and evaluate the cognitive load of assembly workers.A multi-scale research paradigm based on subjective evaluation method is proposed.Three typical task stages are extracted from the process of assembly work.The National Aeronautics and Space Administration Task Load Index(NASA-TLX)scale,PAAS scale and Workload Profile Index Ratings(WP)scale are selected for the design of 3×3 multi-factor mixed experiment.The power spectrum density(PSD)characteris-tics of electroencephalogram(EEG)are utilized to identify the difficulty levels of the three task sta-ges.The relevant indicators of scale applicability are assessed.The results show that in terms of sensitivity,NASA-TLX scale reaches the highest sensitivity(F=999.137,P=0<0.05).In terms of validity,NASA-TLX scale possesses the best concurrent validity(P=0.0255<0.05).In terms of diagnosticity,NASA-TLX scale based on 6 dimensions takes on the best diagnostic performance.In terms of subject acceptability,WP scale performs the worst.According to the analytic hierarchy process(AHP)model,the applicability scores of NASA-TLX scale,PAAS scale and WP scale are determined as 3,2.55 and 1.6714,respectively.Therefore,NASA-TLX scale is regarded as the most suitable subjective evaluation questionnaire for assembly workers,which is also an effective quantitative evaluation method for the cognitive load of assembly workers.
文摘The heavy metal contamination status of Bight of Bonny sea bed sediment w<span>as investigated. Sediment samples were collected from eleven locations grouped into three stations. The samples were analyzed to determine the heavy met</span><span>als (Fe, Pb, Ni, Zn, Mn, Co, Cd, Cu, Cr) concentration using atomic absorption spectrophotometer. Index model analyses, such as geo-accumulation</span> index (I-geo), Enrichment factor (EF), and Pollution load index (PLI) were used for pollution assessment of sea bed sediment. The most predominant heavy metals in the upstream sediment were Fe;13.57 ± 1.838 mg/kg, cobalt;7.987 ± 3.550 mg/kg, and Ni;1.020 ± 0.802 mg/kg, midstream sediment were Fe;8.554 ± 3.010 mg/kg, Co;8.520 ± 4.00 mg/kg, and Ni;1.140 ± 0.879 mg/kg, while the downstream sediment result had Fe;11.12 ± 3.825 mg/kg, Co;7.275 ± 1.700 mg/kg, and Cd;1.025 ± 0.159 /kg. The I-geo results indicate that Cu, Mn, Pb, Cr, Fe, Zn, Ni, and Co were in their background concentrations while Cd had I-geo</span><span style="font-family:""> </span><span style="font-family:"">></span><span style="font-family:""> </span><span style="font-family:"">3 which implies a moderately or heavily polluted env<span>ironment. The EF indicates metal enrichment from anthropogenic sour</span>ces fo<span>r Co, Ni, Pb, Cd, Cu, and Cr while Fe and Mn predicate biogenic origin. The PLI of the heavy metals in the three sample stations of sea bed sediment was found to be generally low (<1). The Enrichment Factor and geo-ac</span>cumulation index strongly suggest the Bight of Bonny sea bed sediment contamination by Cd from anthropogenic sources.
基金Supported by the National Key R&D Programs of China(Nos.2017YFB0504201,2015BAJ02B)the National Natural Science Foundation of China(Nos.61473286,61375002)the Natural Science Foundation of Hainan Province(No.20164178)
文摘The changing patterns of watersheds in a landscape, driven by human activities, play an important role in non-point source pollution processes. This paper aims to improve the location-weighted landscape contrast index using remote sensing and GIS technology to account for the effects of scale and ecological processes. The hydrological response unit(HRU) with a single land use and soil type was used as the smallest unit. The relationship between the landscape index and typical ecological processes was established by describing the influence of the landscape pattern on non-point source pollution. To verify the research method, this paper used the Yanshi River basin as a study area. The results showed that the relative intensity of non-point source pollution in different regions of the watershed and the location-weighted landscape contrast index based on the minimum HRU can qualitatively reflect the risk of regional nutrient loss.
文摘The study of the ecological system (ES) reaction to anthropogenous loading (AL) has been aimed at developing the remote sensing method for quantitative mapping of AL on ES. The analysis of the problem has shown that the main approach for its solution is to assess the amount of entropy induced in ES by AL. The general formalism has been dis-cussed and the thermodynamic index of ES health disturbance (TIEHD- ) has been deduced from the conservation law as a portion of solar exergy spent by ES on the parrying entropy formed in ES due to AL with respect to the total amount of exergy of solar irradiations absorbed by ES. The technique of remote mapping of TIEHD has been developed. The maps of TIEHD and the normalized differential vegetation index (NDVI)- have been compiled on the basis of NOAA and EOS satellite data. The qualitative and quantitative analysis exhibited the best sensitivity of TIEHD to AL on ES in respect to NDVI.
文摘The expansion planning and operation of all three sectors, generation, transmission and distribution, of power system essentially require load forecasting. Weather conditions have significant impacts on forecasted load, especially short-term and mid-term. A momentous portion of the electrical energy is consumed, especially in cold or hot countries, to mitigate the impact of weather on the daily life of human society. Usually, weather dependent component of load is identified by fitting appropriate non-linear curve to the scatter plot of weather-load model. This technique some times shows lower correlation with weather variables. This paper proposes a new methodology to identify the weather sensitive component of electrical load using empirical mode decomposition (EMD) technique. The proposed methodology is applied to the daily peak load of Dhaka zone of Bangladesh Power System (BPS) of the year 2012. A detailed numerical process to evaluate the weather sensitive portion of the load is also presented. The proposed methodology is validated through statistical error evaluation process. Finally the salient features of the results are discussed.
文摘Harmonic content of the voltage source inverters is important and must be in the allowed ranges. Different method are proposed to decrease the Total Harmonic Distortion (THD) and caused to be sinusoidal the output voltage of inverters. One of these methods is using multilevel structure. In this structure many important parameters which are effective on voltage source inverter operation that among them we can mention to modulation index (MI). Variation of modulation index can change the THD. One of the harmonic reduction methods is using multilevel structure. In this paper, a sample 5-level SHE-PWM voltage source inverter is presented and all equation and choosing switching angles for elimination desired harmonics from different order. To investigate the effective parameters on the inverter operation, a typical 5-level inverter is simulated in PSPICE software. The simulation has been done for different values of modulation and its effect on the inverter operation is evaluated.
