efficiency

摘要： In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the experimental approach and allows for improving the turbine productivity and its design. The analysis of energy losses in the flow part of the turbine Fr500, as well as the analysis of the influence of the opening of the guide vanes on changes in energy losses. The results showed that the greatest losses occur in the guide vane 3.02% based on the two-dimensional model and 2.5% based on the 3D model, which significantly affects the efficiency. The analysis was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulations. With the help of the study, the main energy problem is solved—increasing efficiency.

摘要： The copper indium gallium selenium (CIGS) thin film is widely acknowledged as the most promising material for photovoltaic applications. Mainly due to appealing chemical and physical structures properties, low fabrication cost, high efficiency, and uncomplicated integration especially with the advancement in the use of the flexible substrate. Promising results have been achieved in CIGS-based solar cells in the last few years and these devices could be key in unlocking the potential of green energy. Therefore, it is necessary to understand the parameters that are critical to improving the efficiency of these devices. Parameters such as doping concentration, thickness, substrates, and energy bandgap. In this review, we comprehensively report on these parameters with an aim of showing the recent progress on the various methods used to optimize them, all geared towards efficient and low cost solar cells for PV applications.

摘要： BACKGROUND Endoscopic procedures are becoming increasingly important for the diagnosis and treatment of gastrointestinal disorders during childhood,and have evolved from a more infrequent inpatient procedure in the operating room to a routine outpatient procedure conducted in multiple care settings.Demand for these procedures is rapidly increasing and thus there is a need to perform them in an efficient manner.However,there are little data comparing the efficiency of pediatric endoscopic procedures in diverse clinical environments.We hypothesized that there are significant differences in efficiency between settings.AIM To compare the efficiency and examine adverse effects of pediatric endoscopic procedures across three clinical settings.METHODS A retrospective chart review was conducted on 1623 cases of esophagogastroduodenoscopy(EGD)or combined EGD and colonoscopy performed between January 1,2014 and May 31,2018 by 6 experienced pediatric gastroenterologists in three different clinical settings,including a tertiary care hospital operating room,community hospital operating room,and free-standing pediatric ambulatory endoscopy center at a community hospital.The following strict guidelines were used to schedule patients at all three locations:age greater than 6 mo;American Society of Anesthesiologists class 1 or 2;normal craniofacial anatomy;no anticipated therapeutic intervention(e.g.,foreign body retrieval,stricture dilation);and,no planned or anticipated hospitalization post-procedure.Data on demographics,times,admission rates,and adverse events were collected.Endoscopist time(elapsed time from the endoscopist entering the operating room or endoscopy suite to the next patient entering)and patient time(elapsed time from patient registration to that patient exiting the operating room or endoscopy suite)were calculated to assess efficiency.RESULTS In total,58%of the cases were performed in the tertiary care operating room.The median age of patients was 12 years and the male-to-female ratio was nearly equal across all locations.Endoscopist time at the tertiary care operating room was 12 min longer compared to the community operating room(63.3±21.5 min vs 51.4±18.9 min,P<0.001)and 7 min longer compared to the endoscopy center(vs 56.6±19.3 min,P<0.001).Patient time at the tertiary care operating room was 11 min longer compared to the community operating room(133.2±39.9 min vs 122.3±39.5 min,P<0.001)and 9 min longer compared to the endoscopy center(vs 124.9±37.9 min;P<0.001).When comparing endoscopist and patient times for EGD and EGD/colonoscopies among the three locations,endoscopist,and patient times were again shorter in the community hospital and endoscopy center compared to the tertiary care operating room.Adverse events from procedures occurred in 0.1%(n=2)of cases performed in the tertiary care operating room,with 2.2%(n=35)of cases from all locations having required an unplanned admission after the endoscopy for management of a primary GI disorder.CONCLUSION Pediatric endoscopic procedures can be conducted more efficiently in select patients in a community operating room and endoscopy center compared to a tertiary care operating room.

摘要： In this work, the AFORS-HET digital simulation software was used to calculate the electrical characteristics of the cell/n-ZnO/i-ZnO/n-Zn (O, S)/p-CIGSe2/p + -MoSe2/Mo/SLG. When the thickness of the CIGSe2 absorber is between 3.5 and 1.5 μm, the efficiency of the cell with an interfacial layer of MoSe2 remains almost constant, with an efficiency of about 24.6%, higher to that of a conventional cell which is 23.4% for a thickness of 1.5 μm of CIGSe2. To achieve the expected results, the MoSe2 layer must be very thin less than or equal to 30 nm. In addition, a Schottky barrier height greater than 0.45 eV severely affects the fill factor and the open circuit voltage of the solar cell with MoSe2 interface layer.

摘要： The study of vehicular ad-hoc networks(VANETs)has received significant attention among academia;even so,its security and privacy still become a central issue that is wide-open to discuss.The authentication schemes deployed in VANETs have a substantial impact on its security and privacy.Many researchers have proposed a variety of schemes related to the information verification and efficiency improvement in VANETs.In recent years,many papers have proposed identity-based batch verification(IBV)schemes in regard to diminishing overhead in the message verification process in VANETs.This survey begins with providing background information about VANETs and clarifying its security and privacy,as well as performance requirements that must be satisfied.After presenting an outlook of some relevant surveys of VANETs,a brief review of some IBV schemes published in recent years is conferred.The detailed approach of each scheme,with a comprehensive comparison between them,has been provided afterward.Finally,we summarize those recent studies and possible future improvements.

摘要： All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding properties.However,their practical application is hindered by poor stability.Herein,we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr_(3) QDs by using 2-hexyldecanoic acid(DA)as a ligand to replace the regular oleic acid(OA)ligand.Thanks to the strong binding energy between DA ligand and QDs,the modified QDs not only show a high photoluminescence quantum yield(PLQY)of 96%but also exhibit high stability against ethanol and water.Thereby warm white light-emitting diodes(WLEDs)are constructed by combining lig-and modified CsPbBr_(3) QDs with red AgInZnS QDs on blue emitting InGaN chips,exhibiting a color rendering index of 93,a power efficiency of 64.8 lm/W,a CIE coordinate of(0.44,0.42)and correlated color temperature value of 3018 K.In ad-dition,WLEDs based on ligand modified CsPbBr_(3) QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr_(3) QDs.The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr_(3) QDs are ideal for WLEDs application.

摘要： Investments in the exploitation of the continent’s raw material reserves have resulted in little (positive) impact on the energy security situation within Africa. This paper attempts to explore factors influencing the level of energy security of Small Medium Enterprises (SMEs) in the Greater Accra Region of Ghana, and from the dimension of availability, affordability, economic efficiency and environmental stewardship or sustainability of energy. The cross-sectional survey design was employed as the design for the collection and analysis of data. The study applied a quantitative research method in examining the indicators of energy security for SMEs in Accra Metropolis in the Greater Accra Region of Ghana. The population covered about 500 SMEs who have about 100 employees and total revenue of $1 million or the equivalence in Ghana Cedis. A sample of 246 was selected through a cluster and simple random sampling. The analysis adopted statistical techniques to conduct descriptive, exploratory and inferential analysis of the data collected. Factors that influence the level of energy security of SMEs are broadly categorized into the environment and economic change, political factors, physical disruptions and market conditions. Ge- nerally, the level of energy security under the availability dimension is medium among the SMEs. Issues of affordability, economic efficiency and environmental stewardship provide high medium interventions on energy security for SMEs. It is recommended that managers of Ghana’s energy sector should ensure prudent management of the country’s energy resources since the disruption of supply lines or sources form the key conditions that influence the energy security level of SMEs. SMEs should adopt energy efficiency measures to ensure that energy is conserved for future use.

摘要： [Objectives]The paper was to compare and verify the operation performance of precision electric mist duster and electric sprayer,and to select the optimum plant protection equipment suitable for greenhouse application.[Methods]Agents were sprayed by precision electric mist duster and electric sprayer to control tomato downy mildew in greenhouse,and the control effect and pesticide utilization rate were compared.[Results]Compared with electric sprayer,precision electric mist duster improved the pesticide utilization rate by 31.7%,improved the spray efficiency by 20 times,and increased the control effect by 13.2%.[Conclusions]The study provides technical support for the popularization and application of precision electric mist duster in greenhouse and other facilities cultivation.

摘要： Silicon(Si)has been regarded as an alternative anode material to traditional graphite owing to its higher theoretical capacity(4200 vs.372 m Ah g;).However,Si anodes suffer from the inherent volume expansion and unstable solid electrolyte interphase,thus experiencing fast capacity decay,which hinders their commercial application.To address this,herein,an endotenon sheathinspired water-soluble double-network binder(DNB)is presented for resolving the bottleneck of Si anodes.The as-developed binder shows excellent adhesion,high mechanical properties,and a considerable self-healing capability mainly benefited by its supramolecular hybrid network.Apart from these advantages,this binder also induces a Li;N/Li F-rich solid electrolyte interface layer,contributing to a superior cycle stability of Si electrodes.As expected,the DNB can achieve mechanically more stable Si electrodes than traditional polyacrylic acid and pectin binders.As a result,DNB delivers superior electrochemical performance ofSi/Li half cells and Li Ni;Co;Mn;O;/Si full cells,even with a high loading of Si electrode,to traditional polyacrylic acid and pectin binders.The bioinspired binder design provides a promising route to achieve long-life Si anode-assembled lithium batteries.

摘要： The remarkable ramping of record power conversion efficiencies in perovskite solar cells(PSCs) has stimulated the growth of this technology towards commercialization. However, there remain challenges and opportunities for further improving their efficiency and stability. Featuring the variety of functional group in the constituting ions, ionic liquids(ILs) exhibit versatile properties and functions that can be leveraged to the development of improved PSCs. Herein with a systematic review on the recent progress in the application of ILs to PSCs, we show that based on the different roles of ILs in the film and device settings, IL can facilitate the thin-film synthesis of perovskites, improve the properties of chargetransport layers, and ameliorate the interfacial energetics at device interfaces. In particular, the ILsperovskite interactions of two different types(Lewis acid-base interaction and hydrogen bonding) are the essential chemistries underpinning observed efficiency and stability improvements in PSCs, which represent a vast research paradigm in the field of energy chemistry.