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Decision-Aided Extended Kalman Filter Based Adaptive Timing Recovery for Wavelet Packet Modulated Signals
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作者 孙懿 郝久玉 《Tsinghua Science and Technology》 SCIE EI CAS 2010年第3期329-334,共6页
One of the major issues with multi-carrier systems is their vulnerability to timing synchronization errors resulting in the loss of time synchronization which causes loss of orientation of incoming data at the receive... One of the major issues with multi-carrier systems is their vulnerability to timing synchronization errors resulting in the loss of time synchronization which causes loss of orientation of incoming data at the receiver. This paper presents an acquisition algorithm to timing recovery using the decision-aided extended Kalman filtering (EKF) technique for nonlinear disturbance channels in a wavelet packet transform-based multicarrier modulation communication system. This timing recovery algorithm gives faster convergence, smaller root mean square (RMS) errors, and better bit error rate (BER) performance than traditional timing recovery methods, such as the phase-locked loop (PLL), maximum likelihood (ML), and Kalman filter (KF) methods. Thus, the algorithm is able to handle larger timing errors more reliably and to provide better timing recovery, since the scheme takes into account the nonlinear relationship between the signal samples and timing errors. Simulations for various time-varying channels show that the timing recovery algorithm works well for wavelet packet transform-based multicarrier modulation communication systems. 展开更多
关键词 wavelet packet transform multi-carrier modulation adaptive timing recovery extended Kalman filter
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Phase composition,conductivity,and sensor properties of cerium-doped indium oxide
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作者 M.I.Ikim G.N.Gerasimov +2 位作者 V.F.Gromov O.J.Ilegbusi L.I.Trakhtenberg 《Nano Materials Science》 EI CAS CSCD 2024年第2期193-200,共8页
The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)... The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)and InOOH are formed,which are the precursors of stable cubic(c-In_(2)O_(3))and metastable rhombohedral(rh-In_(2)O_(3))phases,respectively.A transition from c-In_(2)O_(3)to rh-In_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-In_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-In_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-In_(2)O_(3).The reverse situation is observed in composites based on c-In_(2)O_(3).Compared to In_(2)O_(3)and CeO_(2)–In_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between In_(2)O_(3)and CeO_(2). 展开更多
关键词 Cerium oxide Indium oxide NANOCOMPOSITE Hydrothermal method Cubic phase Rhombohedral phase Sensor response CONDUCTIVITY HYDROGEN Response/recovery time
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Cyberattack Ramifications, The Hidden Cost of a Security Breach
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作者 Meysam Tahmasebi 《Journal of Information Security》 2024年第2期87-105,共19页
In this in-depth exploration, I delve into the complex implications and costs of cybersecurity breaches. Venturing beyond just the immediate repercussions, the research unearths both the overt and concealed long-term ... In this in-depth exploration, I delve into the complex implications and costs of cybersecurity breaches. Venturing beyond just the immediate repercussions, the research unearths both the overt and concealed long-term consequences that businesses encounter. This study integrates findings from various research, including quantitative reports, drawing upon real-world incidents faced by both small and large enterprises. This investigation emphasizes the profound intangible costs, such as trade name devaluation and potential damage to brand reputation, which can persist long after the breach. By collating insights from industry experts and a myriad of research, the study provides a comprehensive perspective on the profound, multi-dimensional impacts of cybersecurity incidents. The overarching aim is to underscore the often-underestimated scope and depth of these breaches, emphasizing the entire timeline post-incident and the urgent need for fortified preventative and reactive measures in the digital domain. 展开更多
关键词 Artificial Intelligence (AI) Business Continuity Case Studies Copyright Cost-Benefit Analysis Credit Rating Cyberwarfare Cybersecurity Breaches Data Breaches Denial Of Service (DOS) Devaluation Of Trade Name Disaster recovery Distributed Denial of Service (DDOS) Identity Theft Increased Cost to Raise Debt Insurance Premium Intellectual Property Operational Disruption Patent Post-Breach Customer Protection recovery Point Objective (RPO) recovery Time Objective (RTO) Regulatory Compliance Risk Assessment Service Level Agreement Stuxnet Trade Secret
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Effects of recovery time after fire and fire severity on stand structure and soil of larch forest in the Kanas National Nature Reserve, Northwest China 被引量:4
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作者 LIU Xiaoju PAN Cunde 《Journal of Arid Land》 SCIE CSCD 2019年第6期811-823,共13页
Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of d... Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China. 展开更多
关键词 fire severity recovery time litter mass total basal area soil organic carbon total nitrogen total phosphorus total potassium
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Recovery time of macroinvertebrate community from Cd pollution in Longjiang River,Guangxi,China 被引量:1
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作者 Yongde CUI Baoqiang WANG +2 位作者 Yongjing ZHAO Nick RBOND Hongzhu WANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2022年第1期183-194,共12页
Estimating recovery times from pollution incident is an important issue of targeted biomonitoring programs.In the present study,the impact and recovery of macroinvertebrate communities from a cadmium wastewater discha... Estimating recovery times from pollution incident is an important issue of targeted biomonitoring programs.In the present study,the impact and recovery of macroinvertebrate communities from a cadmium wastewater discharge in the Longjiang River,Guangxi,China,in early January 2012 were studied based on 83 samples collected in fi ve surveys within 20 months after the incident.The pollution aff ected seriously the local aquatic biota,and consequently,the invertebrate abundance and species richness were reduced considerably.Twelve months later,the taxonomic number of macroinvertebrates began to increase.However,sensitive taxa remained rare.Twenty months later,the taxon richness and abundance of macroinvertebrates increased signifi cantly compared to those in the previous four time points.To explore the possible time-scale over which pre-disturbance conditions might occur,we chose four diff erent typical metrics of taxa richness(total taxa number,cumulative taxa number,taxa number per samples,and the Shannon-Wiener diversity index)and extrapolated modeled recovery trajectories.Target values for the four metrics were set at average values for sites from the nearby Lijiang River,which were used as a reference.Assuming a continued linear trajectory,the recovery times were estimated to be 52,39,39,and 31 months,respectively,which was roughly 3-5 years.This is consistent with results from recovery times from other studies of acute pollution cases,but contrasted strongly to the much longer recovery times associated with chronic pollution from groundwater contamination and mine-tailing runoff. 展开更多
关键词 macroinvertebrate community recovery time heavy metal pollution CADMIUM Longjiang River
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Investigation of current collapse and recovery time due to deep level defect traps inβ-Ga2O3 HEMT 被引量:1
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作者 R.Singh T.R.Lenka +3 位作者 R.T.Velpula B.Jain H.Q.T.Bui H.P.T.Nguyen 《Journal of Semiconductors》 EI CAS CSCD 2020年第10期87-90,共4页
In this paper,drain current transient characteristics ofβ-Ga2O3 high electron mobility transistor(HEMT)are studied to access current collapse and recovery time due to dynamic population and de-population of deep leve... In this paper,drain current transient characteristics ofβ-Ga2O3 high electron mobility transistor(HEMT)are studied to access current collapse and recovery time due to dynamic population and de-population of deep level traps and interface traps.An approximately 10 min,and 1 h of recovery time to steady-state drain current value is measured under 1 ms of stress on the gate and drain electrodes due to iron(Fe)–dopedβ-Ga2O3 substrate and germanium(Ge)–dopedβ-Ga2O3 epitaxial layer respectively.On-state current lag is more severe due to widely reported defect trap EC–0.82 e V over EC–0.78 e V,-0.75 e V present in Iron(Fe)-dopedβ-Ga2O3 bulk crystals.A negligible amount of current degradation is observed in the latter case due to the trap level at EC–0.98 e V.It is found that occupancy of ionized trap density varied mostly under the gate and gate–source area.This investigation of reversible current collapse phenomenon and assessment of recovery time inβ-Ga2O3 HEMT is carried out through 2 D device simulations using appropriate velocity and charge transport models.This work can further help in the proper characterization ofβ-Ga2O3 devices to understand temporary and permanent device degradation. 展开更多
关键词 β-Ga2O3 current collapse DEGRADATION HEMT recovery time TRAPS trapping effects
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Oscillation in Response and Recovery Properties of SnO_2 Gas Sensor
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作者 Peng Yang Yanfen Wan Quanxi Cao 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2006年第A03期148-151,共4页
Six kinds of Sn(OH)_4 precipitates were prepared by the chemical precipitation method (liquid-phase),of which the pH values are 3.0 (sample 1),4.5 (sample 2),6.0 (sample 3),7.5 (sample 4),9.0 (sample 5) and 10.5 (samp... Six kinds of Sn(OH)_4 precipitates were prepared by the chemical precipitation method (liquid-phase),of which the pH values are 3.0 (sample 1),4.5 (sample 2),6.0 (sample 3),7.5 (sample 4),9.0 (sample 5) and 10.5 (sample 6),respectively. After washed and dried,the Sn(OH)_4 precipitates were first calcined into tin oxide powder.Six kinds of gas sensors were made from the obtained SnO_2 powders.The XRD patterns of all the samples were recorded.The sensing properties of all samples to C_2H_5OH and H_2 gases were measured in different gas concentrations and temperatures,including the sensitivities of all samples,their response and recovery properties.The recovery properties of all samples to C_2H_5OH exhibit the sinusoidal oscillation character. 展开更多
关键词 SnO2 gas sensor sensitivity response time recovery time OSCILLATION
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Effect of Locking Compression Plate on the Treatment of Limb Fracture and the Effect of Operative Success Rate and Postoperative Recovery Time
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作者 Hanping Huang 《Journal of Integrative Medicine(双语)》 2020年第1期9-11,共3页
Objective:To analyze the effect of locking compression plate on the success rate of operation and the time of postoperative recovery.Methods:120 patients with limb fractures from March 2018 to March 2020 were randomly... Objective:To analyze the effect of locking compression plate on the success rate of operation and the time of postoperative recovery.Methods:120 patients with limb fractures from March 2018 to March 2020 were randomly divided into control group(60 cases)and observation group(60 cases).The control group was treated with plate screw internal fixation,The observation group used locking compression plate internal fixation,Compare the effect of treatment,the success rate of operation and the time of postoperative recovery.results:compared the effective rate of the two groups,the observation group(93.33%)was significantly higher than the control group(75.00%).Compared with the two groups,the success rate of operation and the time of postoperative recovery,the observed composition power was higher than that of the control group,and the postoperative recovery time was lower than that of the control group,P<0.05.Conclusion:The use of locking compression plate for the treatment of limb fracture can significantly increase the probability of successful operation,shorten the recovery time after operation,the overall curative effect is ideal,and the clinical popularization value is high. 展开更多
关键词 Limb fracture Locking compression plate internal fixation Plate screw internal fixation EFFECT Surgical success rate Postoperative recovery time
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Time to recovery from severe pneumonia and its predictors among pediatric patients admitted in Mizan-Tepi University Teaching Hospital,South West Ethiopia,2022
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作者 Belete Fenta Kebede Aynalem Yetwale Hiwot +2 位作者 Tsegaw Biyazin Tesfa Yalemtsehay Dagnaw Genie Nigatu Dessalegn Mulu 《Frontiers of Nursing》 2024年第3期343-353,共11页
Objective:Despite trials and programs for the prevention of childhood mortality due to pneumonia,Ethiopia is among the top five countries with the highest number of deaths due to pneumonia.Although the prevalence of p... Objective:Despite trials and programs for the prevention of childhood mortality due to pneumonia,Ethiopia is among the top five countries with the highest number of deaths due to pneumonia.Although the prevalence of pneumonia has increased in the abovementioned trials,little is known about the recovery time from severe pneumonia and its predictors in the study area.Therefore,this study aimed to assess the time to recovery from severe pneumonia and its predictors among pediatric patients admitted to Mizan-Tepi University Teaching Hospital,Ethiopia,in 2022.Methods:A total of 591 children admitted for severe pneumonia were selected using simple random sampling.Data were entered into Epi-data version 4.4.2.1 and expor ted to STATA version 14 for analysis,and the assumptions of Cox propor tional hazard models and goodness of fit were assessed through Shoenfeld residual and Cox-Snell residual,respectively.Bivariate and multivariable Cox regression models were used to identify the predictors of mor tality.Results:This study revealed that 91.54%(95%confidence interval[CI]:89.00–93.53)of participants recovered with an incidence rate of 24.10(95%CI:22.15–26.21)per 100 person-day–observations.The hmedian recovery time of children was 4 days(95%CI:2–6).Children who were not exclusively breastfed(AHR=1.3;95%CI:1.03–1.66),who had a history of inability to suck/feed(AHR=0.81;95%CI:0.65–0.99)were independent predictors of the time to recovery.Conclusions:Children with severe pneumonia who had not exclusively breastfed and who had a history of inability to suck/feed were independent predictors of time to recovery.Therefore,all stakeholders and concerned health care providers should focus more on early diagnosis and management and hasten early recovery based on the identified factors. 展开更多
关键词 Mizan-Tepi University Teaching Hospital pediatric patients predictors severe pneumonia Southwest Ethiopia time to recovery
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A gate enhanced power U-shaped MOSFET integrated with a Schottky rectifier
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作者 王颖 焦文利 +2 位作者 胡海帆 刘云涛 曹菲 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第5期441-444,共4页
An accumulation gate enhanced power U-shaped metal-oxide-semiconductor field-effect-transistor(UMOSFET) integrated with a Schottky rectifier is proposed.In this device,a Schottky rectifier is integrated into each ce... An accumulation gate enhanced power U-shaped metal-oxide-semiconductor field-effect-transistor(UMOSFET) integrated with a Schottky rectifier is proposed.In this device,a Schottky rectifier is integrated into each cell of the accumulation gate enhanced power UMOSFET.Specific on-resistances of 7.7 m.mm 2 and 6.5 m.mm 2 for the gate bias voltages of 5 V and 10 V are achieved,respectively,and the breakdown voltage is 61 V.The numerical simulation shows a 25% reduction in the reverse recovery time and about three orders of magnitude reduction in the leakage current as compared with the accumulation gate enhanced power UMOSFET. 展开更多
关键词 ACCUMULATION Schottky source reverse recovery time leakage current
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Direct Current Circuit Breaker in EAST
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作者 宋执权 傅鹏 《Plasma Science and Technology》 SCIE EI CAS CSCD 2006年第4期481-484,共4页
This paper introduces the configuration and the operation principles of a high power direct current circuit breaker (DCCB). The commutating current principle of the breaker is described in details with its theory an... This paper introduces the configuration and the operation principles of a high power direct current circuit breaker (DCCB). The commutating current principle of the breaker is described in details with its theory and simulation analysis. The test results presented show that the DCCB meets the requirements for quenching protection. It will be used as the main breaker for quench protection in EAST. 展开更多
关键词 direct current circuit breaker insulator recovery time commutating current contact
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A gate enhanced power U-shaped MOSFET integrated with a Schottky rectifier
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作者 王颖 焦文利 +2 位作者 胡海帆 刘云涛 曹菲 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第5期445-448,共4页
An accumulation gate enhanced power U-shaped metal-oxide-semiconductor field-effect-transistor(UMOSFET) integrated with a Schottky rectifier is proposed.In this device,a Schottky rectifier is integrated into each cell... An accumulation gate enhanced power U-shaped metal-oxide-semiconductor field-effect-transistor(UMOSFET) integrated with a Schottky rectifier is proposed.In this device,a Schottky rectifier is integrated into each cell of the accumulation gate enhanced power UMOSFET.Specific on-resistances of 7.7 m.mm 2 and 6.5 m.mm 2 for the gate bias voltages of 5 V and 10 V are achieved,respectively,and the breakdown voltage is 61 V.The numerical simulation shows a 25% reduction in the reverse recovery time and about three orders of magnitude reduction in the leakage current as compared with the accumulation gate enhanced power UMOSFET. 展开更多
关键词 ACCUMULATION Schottky source reverse recovery time leakage current
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On Timing Offset Estimation of OFDM 被引量:1
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作者 XIAO Jian-hua, ZHANG Ping (Wireless Innovation Lab, Beijing University of Posts and Telecommunications, Beijing 100876, P.R. China) 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2003年第1期39-43,共5页
In this paper, a new timing offset estimation method for Orthogonal FrequencyDivision Multiplexing ( OFDM) systems are presented. Upon the receipt of just one trainingsequence, this presence of a signal and the start ... In this paper, a new timing offset estimation method for Orthogonal FrequencyDivision Multiplexing ( OFDM) systems are presented. Upon the receipt of just one trainingsequence, this presence of a signal and the start of the frame can be detected. The performances ofthe timing estimator in additive white Gaussian noise and the mo bile multipath channel areevaluated by simulation . The results delivered by this algorithm are compared with thosedelivered by Schmidl and Cox. 展开更多
关键词 OFDM timing recovery InterSymbol interference (ISI) mobile multipathchannel
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Short circuit analysis of a fault-tolerant current-limiting high temperature superconducting transformer in a power system in presence of distributed generations
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作者 Alireza Sadeghi Shahin Alipour Bonab +1 位作者 Wenjuan Song Mohammad Yazdani-Asrami 《Superconductivity》 2024年第1期74-86,共13页
Power transformers are key elements for the safe and reliable delivery of electrical energy generated by renewable energy resources to consumers via transmission lines.Fault‐tolerant current‐limiting High Temperatur... Power transformers are key elements for the safe and reliable delivery of electrical energy generated by renewable energy resources to consumers via transmission lines.Fault‐tolerant current‐limiting High Temperature Superconducting(FTCL HTS)transformers are type of superconducting transformers that tolerate fault for seconds and limit the fault current without the threat of burnout or delamination of tapes and deformation of windings.In this paper,the fault performance of a FTCL HTS transformer in a standard IEEE power system is investigated.The studied transformer is a 50 MVA 132 kV/13.8 kV transformer where both windings are made up of HTS tapes.The understudied power system consists of two microgrids with distributed generators.Part of the power in microgrids is supplied by the upstream grid which is connected to the microgrids through the HTS transformers.Two fault scenarios have been considered in this power system,in each one of these scenarios,a fault happens in one of the microgrids.Two considered fault scenarios have an approximate fault current of 18x to 23x of the rated current in the secondary windings.Results showed that insulated windings in FTCL HTS transformers could substantially reduce the peak temperature of the HTS windings,compared to bare windings.Afterwards,post‐fault loading is imposed on the HTS windings,to observe their performance against the current increase after fault clearance.In this case,for the first scenario of the faults,the FTCL HTS transformer could tolerate 192%of post‐fault overloading,while this number for the second fault scenario is 170%.Finally,the impact of post‐fault loading on the full recovery time was discussed. 展开更多
关键词 Fault Energy Heat dissipation Heat transfer INSULATION recovery Time Temperature rise
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A comparative study of the dose response and time course of recovery of atracurium and rocuronium 被引量:1
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作者 薛富善 张雁鸣 +2 位作者 廖旭 刘建华 安刚 《Chinese Medical Journal》 SCIE CAS CSCD 2000年第11期59-61,共3页
To compare the characteristics of the dose response relationship and the time course of action between atracurium and rocuronium in adult patients anesthetized with N 2O O 2 fentanyl thiopene Methods Sixty pat... To compare the characteristics of the dose response relationship and the time course of action between atracurium and rocuronium in adult patients anesthetized with N 2O O 2 fentanyl thiopene Methods Sixty patients, ASA grade Ⅰ, aged 18-50 years, scheduled for elective plastic surgery were studied All patients were randomly divided into either the atracurium or rocuronium group General anesthesia was maintained with 60% nitrous oxide and 40% oxygen, thiopentone, and fentanyl Neuromuscular function was assessed using an accelograph with train of four (TOF) stimulation at the wrist every 12 seconds The percentage depression of the first twitch (T 1) was used as the study parameter The dose response relationship of atracurium and rocuronium was determined by the cumulative dose response technique Results According to the dose response curves established by a least squares linear regression, the potency ratio of atracurium to rocuronium was 1∶1 2 There were significant differences in the ED 50 , ED 90 , and ED 95 between the two drugs After the intravenous administration of equipotent doses of both drugs (1 5×ED 95 ), the duration of peak effect, clinical duration, and total duration were significantly different between the two drugs, but their recovery indexes were similar Conclusions Atracurium and rocuronium are low potency nondepolarizing relaxants with intermediate duration As compared to atracurium, the neuromuscular blocking effect of rocuronium was about 20% less potent and its duration of action was shorter 展开更多
关键词 ATRACURIUM ROCURONIUM dose response time course of recovery?
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Adapting Backward Error Recovery to Parallel Real Time Systems
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作者 周笛 《Journal of Computer Science & Technology》 SCIE EI CSCD 1992年第3期257-267,共11页
The problem of adapting backward error recovery to parallel real time systems is discussed in this paper. Because of error propagation among different cooperating processes, an error occurring in one process may influ... The problem of adapting backward error recovery to parallel real time systems is discussed in this paper. Because of error propagation among different cooperating processes, an error occurring in one process may influence some important outputs in other processes. Therefore, a local output has to be delayed until its validity is confirmed globally. Since backward error recovery adopts redundancy of computing time instead of processing equipment, the variation of the actual execution time of a cooperating process may be very large if it works in an unreliable environment. These problems are the primary obstacles to be removed. Previous studies focus their attentions on how to eliminate domino-effect dynamically. But backward error recovery cannot be applied directly in parallel real time systems even under the condition that no domino-effect exists. How to reduce output delays efficiently if no domino-effect remains? How to estimate this delay time? How to calculate the actual execution time of every process and how to schedule these processes under an unstable condition? These problems were omitted in literature unfortunately. The interest of this paper is to provide satisfactory solutions to these problems to make it possible to adopt backward error recovery efficiently in parallel real time systems. 展开更多
关键词 very TIME Adapting Backward Error recovery to Parallel Real Time Systems REAL
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Improved sensing performance of WO_(3) nanoparticles decorated with Ag and Pt nanoparticles 被引量:3
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作者 Dong-Liang Feng Zheng-You Zhu +5 位作者 Ling-Ling Du Xia-Xia Xing Chen Wang Jian Chen Yong-Tao Tian Da-Chi Yang 《Rare Metals》 SCIE EI CAS CSCD 2021年第6期1642-1650,共9页
Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) ... Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) nanoparticles decorated with Ag and Pt bimetals(Ag and Pt/WO_(3) NPs)have been developed via combined hydrolysis and hydrothermal strategies.Such sensors prototypes show high response to acetone(Ra/Rg=250@100×10^(-6),140℃),which is 6.1 fold as high as that of the pristine WO_(3) NPs(Ra/Rg=41@100×10^(-6),140℃).Moreover,the recovery time of Ag and Pt/WO_(3) NPs was reduced from 138 to 13 s compared with that of the pristine WO_(3) NPs.The improved acetone sensing performance may be attributed to that the chemical and electronic sensitization of Ag and Pt to WO_(3) NPs increases adsorbed oxygen species,speeds up the reaction and thus boosts the sensing response.Our strategy that decoration of dual precious metals onto WO_(3) NPs improves the acetone sensing performance may be applied to the gas sensors of other sensing materials. 展开更多
关键词 WO_(3)nanoparticles Ag and Pt bimetals Acetone sensing Chemical sensitization recovery time
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Comparative assessment of the thermal tolerance of spotted stemborer, Chilo partellus (Lepidoptera: Crambidae) and its larval parasitoid, Cotesia sesamiae (Hymenoptera: Braconidae)
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作者 Reyard Mutamiswa Frank Chidawanyika Casper Nyamukondiwa 《Insect Science》 SCIE CAS CSCD 2018年第5期847-860,共14页
Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may af... Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe (Lepi- doptera: Crambidae) and its larval parasitoid, Cotesia sesamiae Cameron (Hymenoptera: Braconidae) using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima (CTmax) in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima (CTmin) in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points (SCPs) for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time (HKDT) and chill-coma recovery time (CCRT) varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance (with respect to lethal temperatures and critical thermal limits) and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments. 展开更多
关键词 chill-coma recovery time climate change critical thermal limits heat knock-down time lethal temperatures supercooling point
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