Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation...Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.展开更多
In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and th...In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and the gradient penalty to achieve data augmentation.To lower the threshold for implementing the proposed method,transfer learning is further introduced.The W-DC-GAN-GP-TL framework is thereby formed.This framework is evaluated on 3 different publicly available datasets to judge the quality of generated data.Through visual comparisons and the examination of two visualization methods(probability density function(PDF)and principal component analysis(PCA)),it is demonstrated that the generated data is hard to distinguish from the real data.The application of generated data for training a battery state model using transfer learning is further evaluated.Specifically,Bi-GRU-based and Transformer-based methods are implemented on 2 separate datasets for estimating state of health(SOH)and state of charge(SOC),respectively.The results indicate that the proposed framework demonstrates satisfactory performance in different scenarios:for the data replacement scenario,where real data are removed and replaced with generated data,the state estimator accuracy decreases only slightly;for the data enhancement scenario,the estimator accuracy is further improved.The estimation accuracy of SOH and SOC is as low as 0.69%and 0.58%root mean square error(RMSE)after applying the proposed framework.This framework provides a reliable method for enriching battery measurement data.It is a generalized framework capable of generating a variety of time series data.展开更多
BACKGROUND As a consequence of the economic crisis,the sociopolitical instability and the advent of the coronavirus disease-19 pandemic,nested challenges faced the Lebanese healthcare system.These have resulted in cri...BACKGROUND As a consequence of the economic crisis,the sociopolitical instability and the advent of the coronavirus disease-19 pandemic,nested challenges faced the Lebanese healthcare system.These have resulted in critical shortages of essential resources,including medications vital for oncologic patients.AIM To assess the ramifications of the ongoing economic crisis on oncology patient care focusing on our outpatient oncology department.METHODS A questionnaire was distributed during the month of February 2022 to oncology patients in Hôtel Dieu de France University Hospital in Beirut during their outpatient therapy.The primary objective was to assess the far-reaching impact of the economic crisis on patient care and the resulting psychological implications.RESULTS Among 182 interviewed patients,31.87%experienced treatment interruption mainly due to acute drug shortages.Despite 87.91%of the patients benefiting from third-party coverage,69.60%had to self-pay for their medications leading to 69.78%of patients perceiving that healthcare was more difficult to access after 2020.Psychologically,one-third of the patients exhibited symptoms of anxiety and/or depression,with 7 patients reporting suicidal ideations.Notably,37.93%of patients who interrupted cancer treatment reported a history of comorbidities,and 89.66%who altered their treatment cited financial difficulties.CONCLUSION Lebanese cancer patients face complex challenges spanning economic,healthcare,and psychological realms.Income inequalities exacerbated by the economic crisis hindered healthcare access.展开更多
COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel s...COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel strains (variants), absence of immunity, and human unawareness. This framework introduces a revised epidemic model, drawing upon mathematical principles. This model incorporates a modified vaccination and lockdown approach to comprehensively depict an epidemics transmission, containment, and decision-making processes within a community. This study aims to provide policymakers with precise information on real-world situations to assist them in making informed decisions about the implementation of lockdown strategies, maintenance variables, and vaccine availability. The suggested model has conducted stability analysis, strength number analysis, and first and second-order derivative analysis of the Lyapunov function and has established the existence and uniqueness of solutions of the proposed models. We examine the combined effects of an effective vaccination campaign and non-pharmaceutical measures such as lockdowns and states of emergency. We rely on the results of this research to assist policymakers in various countries in eradicating the illness by developing more innovative measures to control the outbreak.展开更多
[Objective] The pattern of leaves senescence was studied to provide reference for the planting technology and breeding rice cultivars resistant to premature senescence. [Method] Six hybrid rice cultivars were cultivat...[Objective] The pattern of leaves senescence was studied to provide reference for the planting technology and breeding rice cultivars resistant to premature senescence. [Method] Six hybrid rice cultivars were cultivated under limited and conventional irrigation managements; after the heading of rice, the root activities, nitrogen content in leaves, chlorophyll content （SPAD value）, net photosynthetic rate and the activities of superoxide dismutase （SOD）, peroxidase （POD）, catalase （CAT） were determined. [Result] The rhythms in attenuation of xylem sap flow rate, leaf nitrogen content, chlorophyll content （SPAD value） and net photosynthetic rate of different rice cultivars were significantly different in attenuation starting time, attenuation frequency and attenuation range. Physiological indexes of different cultivars responded inconsistently to water shortage. Extremely significantly positive correlations were found between the decline rates of chlorophyll content and leaf nitrogen content and xylem sap flow rate of roots, the photosynthetic rate and chlorophyll content. The changes in activities of SOD, CAT and POD were different, and responded to water shortage differently in different cultivars. The change dynamic of leaf nitrogen content and chlorophyll content was positively related with the activity dynamic of SOD and CAT. The change dynamic of leaf nitrogen content and chlorophyll content was negatively related with the malondialdehyde （MDA） content. The difference in the attenuation rhythm of physiological indexes of leaves and response to water shortage of different hybrid rice cultivars were related to genotype difference. Increasing roots activities and protecting enzyme activities of leaves benefit to defer attenuation of chlorophyll content and nitrogen content of leaves and to keep stronger photosynthetic function. [Conclusion] The senescence resistance of rice is a combined result of genotype differences and physiological response to environment.展开更多
The arid areas in China are mainly located in North China and NorthwestChina. The North China is the main region for food production. There is 31. 19% of the totalfarmland and 26. 01% of the total population, but only...The arid areas in China are mainly located in North China and NorthwestChina. The North China is the main region for food production. There is 31. 19% of the totalfarmland and 26. 01% of the total population, but only 6. 14% of the available water resources ofChina. Groundwater is over pumped (6. 53 X 10~9m^3 every year) in the regions of Beijing, Tianjin,and Hebei Province, so water supply could not meet the water demand there. The distribution of waterin Northwest China is uneven, some inland rivers and lakes are dried up, and desertification hasexpanded since river water in the upper and middle reaches is diverted for irrigation. Up to 2050,population will be up to 1. 6 X 10~9 in China, and industry will be developed fast, therefore 50% ofthe water supply will be used by industry and resident, and water for agriculture will be decreasedyear by year. In the coming 50 years, water demand for agriculture will be increased by 5. 6 x10^9m^3 in the Huanghe (Yellow) River valley, and by 1. 7 x 10~9m^3 in the Northwest China. It willbe impossible for the Huanghe River to meet the water demand, because it always dried up in the coldhalf year since 1984. To avoid water shortage of agriculture in the arid regions, it is necessaryto divert water from the Changjiang (Yangtze) River in the south of China, and to use waterefficiently. It is the best way to use drip irrigation in agriculture, recycle water in industry andresident use, and control water pollution. Otherwise water shortage in the arid regions willrestrict the development of agriculture in China.展开更多
In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solut...In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solution procedure is shown for determining the optimal order lot size and the optimal order cycle. A numerical example is used to illustrate how the solution procedure works.展开更多
Background: There is little disagreement that the shortage of nurses affects patients’ outcomes globally. However, within the low and middle income country setting, there is minimal known about the perceptions of nur...Background: There is little disagreement that the shortage of nurses affects patients’ outcomes globally. However, within the low and middle income country setting, there is minimal known about the perceptions of nurses on nursing shortages impact the health outcomes of their patients and what recruitment and retention strategies might be appropriate to address some of these challenges. This study explored the perceptions of nurses on the health outcomes of patient related to shortage of registered nurses and the strategies to retain nurses at a public hospital in Tanzania. Method: This qualitative descriptive study used semi-structured in-depth interviews with a select group of nurses in a large public hospital. Findings: Through an iterative coding process, a series of categories were derived which yielded three major themes—factors contributing to nursing shortage;compromised quality of care;and recruitment and retention strategies. Conclusion: A shortage of nurses affects the health outcomes of patients as it potentially hinders timely accomplishment of the optimal nursing. Efforts need to be proactive in recognizing the reasons for nursing shortages which are rooted in individual, institutional (agency), and organizational (systemic) issues. Within the LMIC context, such as where this study was conducted, it became apparent that the nurses wanted acknowledgement and opportunities to work collaboratively towards the resolution of workload issues for the benefit of the patients.展开更多
There are increasing demands for mobile health applications. This paper reports the development of a mobile health profile which dedicates to mobile applications. The mobile health profile is developed in association ...There are increasing demands for mobile health applications. This paper reports the development of a mobile health profile which dedicates to mobile applications. The mobile health profile is developed in association with the ZigBee Health Care profile and the IEEE 11073 standard which is normally applied to non-mobile applications. Since mobile sensors have to be carried by patients, the mobile health profile must facilitate mobility. In this investigation, a ZigBee fixed-mobile network (ZFMN) is defined and developed to supplement the ZigBee Health Care Profile for patient monitoring. The mobility study of ZigBee is performed using a random waypoint OPNET simulation model. In a ZFMN, the critical issue of address shortage is identified and discussed. It is analyzed that the problematic address shortage in a ZFMN may generate a huge amount of orphaned end devices and thus the packet drop percentage may potentially rise to 70%, rendering the network unable to function properly. Without introducing additional governing schemes, it is evaluated that the communication of the entire ZigBee network may paralyze. Further vigorous test are performed (by OPNET) on the communication capability of ZFMN when devices are randomly moving and sending data in 1s. It is vital to point out that under the adverse condition of address shortage, the performance of a ZFMN is still encouraging as long as the packet drop percentage has been kept below 3% before running out of address. The conclusion drawn in this analysis is that the packet drop percentage should be kept below 3% to provide a satisfactory QoS for an effective mobile health application using ZFMN such as patient monitoring. Such finding is also important for other future mobile application design of ZigBee. The address shortage issue is left as an open problem that needs attention for a resolution.展开更多
China has experienced a rapid urbanization since late 1970s. The great increase of urban population has resulted in various environmental changes, of which urban water shortage and water environment problems have occu...China has experienced a rapid urbanization since late 1970s. The great increase of urban population has resulted in various environmental changes, of which urban water shortage and water environment problems have occurred in most cities, especially in the rapidly developing urban agglomerations in the eastern coastal region. This research, taking Shandong Peninsula Urban Agglomeration （SPUA） as a case study area analyzes the urbanization expansion in the last decades, discusses the water shortage and water environment changes following the rapid economic development and urbanization sueh as groundwater sinking in the urban and plain area, sea water and saltwater intrusion in the coastal cities, water pollution overspreading and water ecosystem degradation, and puts forwards some strategies for sustainabilitv in populous regions with severe water shortage. Some countermeasures for sustainable development of SPUA are put forward, such as constructing modern water resources inter-city networks to regulate water resouree between cities, adjnsting urbanization policy and urban scale planning to promote the development of small towns and medium sized cities, optimizing urban industry structure by restricting high water consumption enterprises and stimulating the growth of tertiary industry. improving water use efficiency to rednce fresh water consumption and wastewater discharge, introducing economic means to water pricing and water management system, and restoring ecological conditions to strengthen the natural water-making capacity.展开更多
In this paper. an oscillated model.which results from the shortage action in market economy with elastic replacement of goods is obtained.And some naturalrelations between the model and a typically oscillatory model a...In this paper. an oscillated model.which results from the shortage action in market economy with elastic replacement of goods is obtained.And some naturalrelations between the model and a typically oscillatory model are established Theresults can interpret some market phenomena and provied the theoretical tools for theeconomic program.展开更多
China is not abandantly supplied with freshwater. Water shortage is a crucial problem in northern China, and affects the development of economy and causes a host of environmental and ecological problems. Water saving,...China is not abandantly supplied with freshwater. Water shortage is a crucial problem in northern China, and affects the development of economy and causes a host of environmental and ecological problems. Water saving, water resource protection, strengthening of management and exploitation of new water resources are some of the major measures for solving the water shortage problem. Wastewater reuse is also a feasible and practical means of alleviating the problem.展开更多
This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the ext...This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the extent of hardship and high costs the residential will suffer and endure. These outages occur and extend for longer durations. To mitigate these consequences, a method is suggested known as “willingness-to-pay” to seek the ability and willingness of consumers to pay to avert these power outages and energy shortages. Two approaches have been developed and utilized. The first one is based on a consumer survey to estimate his perceived costs. Outages occur in specific periods and last for longer durations. The second approach focussed on developing a mathematical model to complement the survey approach as this model can decrease the size of the problem complexity associated with consumer lack of experience in evaluating and assessing the worth of service reliability and quality.展开更多
This study examined the effectiveness of distance education compared with campus based learning among nursing students. Distance education in nursing curricula is increasing. Academic nurse leaders must demonstrate th...This study examined the effectiveness of distance education compared with campus based learning among nursing students. Distance education in nursing curricula is increasing. Academic nurse leaders must demonstrate the effectiveness of distance learning. This study is unique in that two cohorts, distance learners and campus learners, were taught synchronously by the same faculty member. Quantitative measures of student learning outcomes were compared using SPSS. There were no significant differences in learning outcomes between distance learners and campus learners. This study provides empiric support for distance education as a means to address the nursing shortage.展开更多
Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrializ...Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrialization sometimes makes the power supply still unable to meet the demand.Using a survey of 1673 Chinese manufacturing firms,this paper explores how firms response to electricity shortages and its impact on productivity.We find that self-generation of electricity and investment in Research and Development(R&D)have significant positive relationships with electricity shortages.Further investigations reveal that self-generation is the most common way to deal with electricity shortages.However,it aggravates productivity loss.Though investment in Research and Development can promote productivity,it cannot offset the negative impact of electricity shortages on productivity.Analyses on subsamples show heterogeneity in the impacts of electricity shortages across firms.In particular,large firms are more inclined to invest in R&D than small and medium-sized firms are.They are also the one who suffer significant productivity loss due to self-generation of electricity.Though it is possible for medium-sized firms to reduce productivity loss through R&D,they are not likely to invest in R&D as a response to electricity shortages.This study illustrates that firms can hardly have effective solutions to electricity shortages,and policy makers should take great efforts to increase electricity supply.展开更多
A large magnitude-9.0 earthquake struck northeast Japan on March 11, 2011. Thirty minutes later, a tsunami reached Tokyo Electric Power Corporation （TEPCO）＇s Fukushima Daiichi nuclear power station, and the emergen...A large magnitude-9.0 earthquake struck northeast Japan on March 11, 2011. Thirty minutes later, a tsunami reached Tokyo Electric Power Corporation （TEPCO）＇s Fukushima Daiichi nuclear power station, and the emergency diesel generators submerged under water. Three units of the reactor experienced meltdown, and hydrogen explosions occurred at reactor houses. The RIKEN Nishina Center （RNC） contributed to the radiation screening effort by providing human resources, instruments, and transportation. The RNC also carried out extraction work and sample tests for soil contamination. Last summer, RIKEN was legally required to save 15% （equivalent to 3.3 MW） of its allocated electricity in its contract, making it extremely difficult to conduct experiments using accelerators. Accelerator operation was thus reduced to a minimum during the first half of the year. The RNC has a gas-turbine-based co-generation system （CGS） with an electrical capacity of 6.5 MW. The CGS was operated non-stop until the end of the year. RIKEN is constructing two sets of CGSs, each with a capacity of 1.5 MW to be commissioned this autumn.展开更多
The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spon...The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spontaneous adjustment by the migrant labor market. As rural welfare was greatly enhanced in 2009, migrant workers＇ opportunity cost of working outside their hometowns was raised. The connotation of migrant workers＇ ＂market price＂ is changing. The new generation of migrant workers, namely, those born after 1980, are becoming the mainstay of enterprises＇ employment. Being better educated, they have different lifestyles than previous generations. ＂Leisure and entertainment＂ have become part of their opportunity cost and reduced their labor supply. ＂Labor shortage＂ is an endogenous force that helps transform China＇s growth patter, upgrade the industrial structure and promote urbanization. The seasonal ＂return of migrant workers＂ and the ＂labor shortage＂ which appears around China＇s Spring Festival each year have grown into a unique b,t effective collective bargaining mechanism that helps increase migrant workers＇ wages. Facing labor shortages, governments should regulate the labor market pricing and orientate labor-intensive enterprises towards transition, continue to enhance the social security system for migrant workers and those in rural areas, and make an accurate forecast of the population trend and adjust population policies.展开更多
The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly s...The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly supported by solid merchandise export growth.At the same time,soaring coal prices have hit power producers curtailing growth in electricity supply.展开更多
The government has decided on a two-pronged drive to solve thecountry’s protracted energy shortage by bolstering investment projectswhile tightening control power consumption.Power generating projects costing some 20...The government has decided on a two-pronged drive to solve thecountry’s protracted energy shortage by bolstering investment projectswhile tightening control power consumption.Power generating projects costing some 20 billion yuan (4.26 billion)make up about one-third of the total 68 large and medium-sized capitalconstruction projects approved recently by the State Council despite theausterity policy.All the projects are expected to be completed within threeto eight years.With the completion of the 20 large and medium-sizedprojects,10,500 MW of generating capacity and 530 km of 500 kV trans-mission lines and corresponding substations will be added to the nation’scombined installed generating and transmitting capacity.Three of the projects,with a total installed capacity of 4140 MW。展开更多
基金funded by the Technology Project of State Grid Corporation of China(Research on Safety and Stability Evaluation and Optimization Enhancement Technology of Flexible Ultra High Voltage Multiterminal DC System Adapting to the Background of“Sand and Gobi Deserts”),grant number J2024003。
文摘Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.
基金funded by the Bavarian State Ministry of Science,Research and Art(Grant number:H.2-F1116.WE/52/2)。
文摘In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and the gradient penalty to achieve data augmentation.To lower the threshold for implementing the proposed method,transfer learning is further introduced.The W-DC-GAN-GP-TL framework is thereby formed.This framework is evaluated on 3 different publicly available datasets to judge the quality of generated data.Through visual comparisons and the examination of two visualization methods(probability density function(PDF)and principal component analysis(PCA)),it is demonstrated that the generated data is hard to distinguish from the real data.The application of generated data for training a battery state model using transfer learning is further evaluated.Specifically,Bi-GRU-based and Transformer-based methods are implemented on 2 separate datasets for estimating state of health(SOH)and state of charge(SOC),respectively.The results indicate that the proposed framework demonstrates satisfactory performance in different scenarios:for the data replacement scenario,where real data are removed and replaced with generated data,the state estimator accuracy decreases only slightly;for the data enhancement scenario,the estimator accuracy is further improved.The estimation accuracy of SOH and SOC is as low as 0.69%and 0.58%root mean square error(RMSE)after applying the proposed framework.This framework provides a reliable method for enriching battery measurement data.It is a generalized framework capable of generating a variety of time series data.
文摘BACKGROUND As a consequence of the economic crisis,the sociopolitical instability and the advent of the coronavirus disease-19 pandemic,nested challenges faced the Lebanese healthcare system.These have resulted in critical shortages of essential resources,including medications vital for oncologic patients.AIM To assess the ramifications of the ongoing economic crisis on oncology patient care focusing on our outpatient oncology department.METHODS A questionnaire was distributed during the month of February 2022 to oncology patients in Hôtel Dieu de France University Hospital in Beirut during their outpatient therapy.The primary objective was to assess the far-reaching impact of the economic crisis on patient care and the resulting psychological implications.RESULTS Among 182 interviewed patients,31.87%experienced treatment interruption mainly due to acute drug shortages.Despite 87.91%of the patients benefiting from third-party coverage,69.60%had to self-pay for their medications leading to 69.78%of patients perceiving that healthcare was more difficult to access after 2020.Psychologically,one-third of the patients exhibited symptoms of anxiety and/or depression,with 7 patients reporting suicidal ideations.Notably,37.93%of patients who interrupted cancer treatment reported a history of comorbidities,and 89.66%who altered their treatment cited financial difficulties.CONCLUSION Lebanese cancer patients face complex challenges spanning economic,healthcare,and psychological realms.Income inequalities exacerbated by the economic crisis hindered healthcare access.
文摘COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel strains (variants), absence of immunity, and human unawareness. This framework introduces a revised epidemic model, drawing upon mathematical principles. This model incorporates a modified vaccination and lockdown approach to comprehensively depict an epidemics transmission, containment, and decision-making processes within a community. This study aims to provide policymakers with precise information on real-world situations to assist them in making informed decisions about the implementation of lockdown strategies, maintenance variables, and vaccine availability. The suggested model has conducted stability analysis, strength number analysis, and first and second-order derivative analysis of the Lyapunov function and has established the existence and uniqueness of solutions of the proposed models. We examine the combined effects of an effective vaccination campaign and non-pharmaceutical measures such as lockdowns and states of emergency. We rely on the results of this research to assist policymakers in various countries in eradicating the illness by developing more innovative measures to control the outbreak.
基金Supported by National Natural Science Foundation of China(30860137)the Fund from the Education Department of Jiangxi Province(GJJ09168)~~
文摘[Objective] The pattern of leaves senescence was studied to provide reference for the planting technology and breeding rice cultivars resistant to premature senescence. [Method] Six hybrid rice cultivars were cultivated under limited and conventional irrigation managements; after the heading of rice, the root activities, nitrogen content in leaves, chlorophyll content （SPAD value）, net photosynthetic rate and the activities of superoxide dismutase （SOD）, peroxidase （POD）, catalase （CAT） were determined. [Result] The rhythms in attenuation of xylem sap flow rate, leaf nitrogen content, chlorophyll content （SPAD value） and net photosynthetic rate of different rice cultivars were significantly different in attenuation starting time, attenuation frequency and attenuation range. Physiological indexes of different cultivars responded inconsistently to water shortage. Extremely significantly positive correlations were found between the decline rates of chlorophyll content and leaf nitrogen content and xylem sap flow rate of roots, the photosynthetic rate and chlorophyll content. The changes in activities of SOD, CAT and POD were different, and responded to water shortage differently in different cultivars. The change dynamic of leaf nitrogen content and chlorophyll content was positively related with the activity dynamic of SOD and CAT. The change dynamic of leaf nitrogen content and chlorophyll content was negatively related with the malondialdehyde （MDA） content. The difference in the attenuation rhythm of physiological indexes of leaves and response to water shortage of different hybrid rice cultivars were related to genotype difference. Increasing roots activities and protecting enzyme activities of leaves benefit to defer attenuation of chlorophyll content and nitrogen content of leaves and to keep stronger photosynthetic function. [Conclusion] The senescence resistance of rice is a combined result of genotype differences and physiological response to environment.
文摘The arid areas in China are mainly located in North China and NorthwestChina. The North China is the main region for food production. There is 31. 19% of the totalfarmland and 26. 01% of the total population, but only 6. 14% of the available water resources ofChina. Groundwater is over pumped (6. 53 X 10~9m^3 every year) in the regions of Beijing, Tianjin,and Hebei Province, so water supply could not meet the water demand there. The distribution of waterin Northwest China is uneven, some inland rivers and lakes are dried up, and desertification hasexpanded since river water in the upper and middle reaches is diverted for irrigation. Up to 2050,population will be up to 1. 6 X 10~9 in China, and industry will be developed fast, therefore 50% ofthe water supply will be used by industry and resident, and water for agriculture will be decreasedyear by year. In the coming 50 years, water demand for agriculture will be increased by 5. 6 x10^9m^3 in the Huanghe (Yellow) River valley, and by 1. 7 x 10~9m^3 in the Northwest China. It willbe impossible for the Huanghe River to meet the water demand, because it always dried up in the coldhalf year since 1984. To avoid water shortage of agriculture in the arid regions, it is necessaryto divert water from the Changjiang (Yangtze) River in the south of China, and to use waterefficiently. It is the best way to use drip irrigation in agriculture, recycle water in industry andresident use, and control water pollution. Otherwise water shortage in the arid regions willrestrict the development of agriculture in China.
文摘In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solution procedure is shown for determining the optimal order lot size and the optimal order cycle. A numerical example is used to illustrate how the solution procedure works.
文摘Background: There is little disagreement that the shortage of nurses affects patients’ outcomes globally. However, within the low and middle income country setting, there is minimal known about the perceptions of nurses on nursing shortages impact the health outcomes of their patients and what recruitment and retention strategies might be appropriate to address some of these challenges. This study explored the perceptions of nurses on the health outcomes of patient related to shortage of registered nurses and the strategies to retain nurses at a public hospital in Tanzania. Method: This qualitative descriptive study used semi-structured in-depth interviews with a select group of nurses in a large public hospital. Findings: Through an iterative coding process, a series of categories were derived which yielded three major themes—factors contributing to nursing shortage;compromised quality of care;and recruitment and retention strategies. Conclusion: A shortage of nurses affects the health outcomes of patients as it potentially hinders timely accomplishment of the optimal nursing. Efforts need to be proactive in recognizing the reasons for nursing shortages which are rooted in individual, institutional (agency), and organizational (systemic) issues. Within the LMIC context, such as where this study was conducted, it became apparent that the nurses wanted acknowledgement and opportunities to work collaboratively towards the resolution of workload issues for the benefit of the patients.
文摘There are increasing demands for mobile health applications. This paper reports the development of a mobile health profile which dedicates to mobile applications. The mobile health profile is developed in association with the ZigBee Health Care profile and the IEEE 11073 standard which is normally applied to non-mobile applications. Since mobile sensors have to be carried by patients, the mobile health profile must facilitate mobility. In this investigation, a ZigBee fixed-mobile network (ZFMN) is defined and developed to supplement the ZigBee Health Care Profile for patient monitoring. The mobility study of ZigBee is performed using a random waypoint OPNET simulation model. In a ZFMN, the critical issue of address shortage is identified and discussed. It is analyzed that the problematic address shortage in a ZFMN may generate a huge amount of orphaned end devices and thus the packet drop percentage may potentially rise to 70%, rendering the network unable to function properly. Without introducing additional governing schemes, it is evaluated that the communication of the entire ZigBee network may paralyze. Further vigorous test are performed (by OPNET) on the communication capability of ZFMN when devices are randomly moving and sending data in 1s. It is vital to point out that under the adverse condition of address shortage, the performance of a ZFMN is still encouraging as long as the packet drop percentage has been kept below 3% before running out of address. The conclusion drawn in this analysis is that the packet drop percentage should be kept below 3% to provide a satisfactory QoS for an effective mobile health application using ZFMN such as patient monitoring. Such finding is also important for other future mobile application design of ZigBee. The address shortage issue is left as an open problem that needs attention for a resolution.
基金the National Social Science Fund of China（Grant No.06BJL036）Natural Science Foundation of Shandong Province （Grant No.Y2006E05）.
文摘China has experienced a rapid urbanization since late 1970s. The great increase of urban population has resulted in various environmental changes, of which urban water shortage and water environment problems have occurred in most cities, especially in the rapidly developing urban agglomerations in the eastern coastal region. This research, taking Shandong Peninsula Urban Agglomeration （SPUA） as a case study area analyzes the urbanization expansion in the last decades, discusses the water shortage and water environment changes following the rapid economic development and urbanization sueh as groundwater sinking in the urban and plain area, sea water and saltwater intrusion in the coastal cities, water pollution overspreading and water ecosystem degradation, and puts forwards some strategies for sustainabilitv in populous regions with severe water shortage. Some countermeasures for sustainable development of SPUA are put forward, such as constructing modern water resources inter-city networks to regulate water resouree between cities, adjnsting urbanization policy and urban scale planning to promote the development of small towns and medium sized cities, optimizing urban industry structure by restricting high water consumption enterprises and stimulating the growth of tertiary industry. improving water use efficiency to rednce fresh water consumption and wastewater discharge, introducing economic means to water pricing and water management system, and restoring ecological conditions to strengthen the natural water-making capacity.
文摘In this paper. an oscillated model.which results from the shortage action in market economy with elastic replacement of goods is obtained.And some naturalrelations between the model and a typically oscillatory model are established Theresults can interpret some market phenomena and provied the theoretical tools for theeconomic program.
文摘China is not abandantly supplied with freshwater. Water shortage is a crucial problem in northern China, and affects the development of economy and causes a host of environmental and ecological problems. Water saving, water resource protection, strengthening of management and exploitation of new water resources are some of the major measures for solving the water shortage problem. Wastewater reuse is also a feasible and practical means of alleviating the problem.
文摘This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the extent of hardship and high costs the residential will suffer and endure. These outages occur and extend for longer durations. To mitigate these consequences, a method is suggested known as “willingness-to-pay” to seek the ability and willingness of consumers to pay to avert these power outages and energy shortages. Two approaches have been developed and utilized. The first one is based on a consumer survey to estimate his perceived costs. Outages occur in specific periods and last for longer durations. The second approach focussed on developing a mathematical model to complement the survey approach as this model can decrease the size of the problem complexity associated with consumer lack of experience in evaluating and assessing the worth of service reliability and quality.
文摘This study examined the effectiveness of distance education compared with campus based learning among nursing students. Distance education in nursing curricula is increasing. Academic nurse leaders must demonstrate the effectiveness of distance learning. This study is unique in that two cohorts, distance learners and campus learners, were taught synchronously by the same faculty member. Quantitative measures of student learning outcomes were compared using SPSS. There were no significant differences in learning outcomes between distance learners and campus learners. This study provides empiric support for distance education as a means to address the nursing shortage.
基金supported by“Philosophy and Social Sciences Planned Project of Anhui Province,China”(Grant No.AHSKY2020D37).
文摘Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrialization sometimes makes the power supply still unable to meet the demand.Using a survey of 1673 Chinese manufacturing firms,this paper explores how firms response to electricity shortages and its impact on productivity.We find that self-generation of electricity and investment in Research and Development(R&D)have significant positive relationships with electricity shortages.Further investigations reveal that self-generation is the most common way to deal with electricity shortages.However,it aggravates productivity loss.Though investment in Research and Development can promote productivity,it cannot offset the negative impact of electricity shortages on productivity.Analyses on subsamples show heterogeneity in the impacts of electricity shortages across firms.In particular,large firms are more inclined to invest in R&D than small and medium-sized firms are.They are also the one who suffer significant productivity loss due to self-generation of electricity.Though it is possible for medium-sized firms to reduce productivity loss through R&D,they are not likely to invest in R&D as a response to electricity shortages.This study illustrates that firms can hardly have effective solutions to electricity shortages,and policy makers should take great efforts to increase electricity supply.
文摘A large magnitude-9.0 earthquake struck northeast Japan on March 11, 2011. Thirty minutes later, a tsunami reached Tokyo Electric Power Corporation （TEPCO）＇s Fukushima Daiichi nuclear power station, and the emergency diesel generators submerged under water. Three units of the reactor experienced meltdown, and hydrogen explosions occurred at reactor houses. The RIKEN Nishina Center （RNC） contributed to the radiation screening effort by providing human resources, instruments, and transportation. The RNC also carried out extraction work and sample tests for soil contamination. Last summer, RIKEN was legally required to save 15% （equivalent to 3.3 MW） of its allocated electricity in its contract, making it extremely difficult to conduct experiments using accelerators. Accelerator operation was thus reduced to a minimum during the first half of the year. The RNC has a gas-turbine-based co-generation system （CGS） with an electrical capacity of 6.5 MW. The CGS was operated non-stop until the end of the year. RIKEN is constructing two sets of CGSs, each with a capacity of 1.5 MW to be commissioned this autumn.
文摘The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spontaneous adjustment by the migrant labor market. As rural welfare was greatly enhanced in 2009, migrant workers＇ opportunity cost of working outside their hometowns was raised. The connotation of migrant workers＇ ＂market price＂ is changing. The new generation of migrant workers, namely, those born after 1980, are becoming the mainstay of enterprises＇ employment. Being better educated, they have different lifestyles than previous generations. ＂Leisure and entertainment＂ have become part of their opportunity cost and reduced their labor supply. ＂Labor shortage＂ is an endogenous force that helps transform China＇s growth patter, upgrade the industrial structure and promote urbanization. The seasonal ＂return of migrant workers＂ and the ＂labor shortage＂ which appears around China＇s Spring Festival each year have grown into a unique b,t effective collective bargaining mechanism that helps increase migrant workers＇ wages. Facing labor shortages, governments should regulate the labor market pricing and orientate labor-intensive enterprises towards transition, continue to enhance the social security system for migrant workers and those in rural areas, and make an accurate forecast of the population trend and adjust population policies.
文摘The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly supported by solid merchandise export growth.At the same time,soaring coal prices have hit power producers curtailing growth in electricity supply.
文摘The government has decided on a two-pronged drive to solve thecountry’s protracted energy shortage by bolstering investment projectswhile tightening control power consumption.Power generating projects costing some 20 billion yuan (4.26 billion)make up about one-third of the total 68 large and medium-sized capitalconstruction projects approved recently by the State Council despite theausterity policy.All the projects are expected to be completed within threeto eight years.With the completion of the 20 large and medium-sizedprojects,10,500 MW of generating capacity and 530 km of 500 kV trans-mission lines and corresponding substations will be added to the nation’scombined installed generating and transmitting capacity.Three of the projects,with a total installed capacity of 4140 MW。
