Finite-Time Thermodynamic Simulation of Circulating Direct Condensation Heat Recovery on Chillers

A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in series for a centrifugal chiller in the paper. A finite-time thermodynamics method is used to set up the time series simulation model. As a result, an upper bound of recoverable condensation heat for the compound condensing process is obtained which is in good agreement with experimental result. And the result is valuable and useful to optimization design of condensing heat recovery.

Time to recovery from severe pneumonia and its predictors among pediatric patients admitted in Mizan-Tepi University Teaching Hospital,South West Ethiopia,2022

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.

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

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.

Investigation of current collapse and recovery time due to deep level defect traps inβ-Ga2O3 HEMT

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.

Recovery time of macroinvertebrate community from Cd pollution in Longjiang River,Guangxi,China

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.

Spatio-temporal Variations in Plantation Forests'Disturbance and Recovery of Northern Guangdong Province Using Yearly Landsat Time Series Observations(1986-2015)

Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.

An Efficient Crash Recovery Technique for Real-Time Main Memory Database

This paper presents an efficient recovery scheme suitable for real-time mainmemory database. In the recovery scheme, log records are stored in non-volatile RAM which is dividedinto four different partitions based on transaction types. Similarly, a main memory database isdivided into four partitions based data types. When the using ratio of log store area exceeds thethreshold value, checkpoint procedure is triggered. During executing checkpoint procedure, someuseless log records are deleted. During restart recovery after a crash, partition reloading policyis adopted to assure that critical data are reloaded and restored in advance, so that the databasesystem can be brought up before the entire database is reloaded into main memory. Therefore downtime is obvionsly reduced. Simulation experiments show our recovery scheme obviously improves thesystem performance, and does a favor to meet the dtadlints of real-time transactions.

Effect of Locking Compression Plate on the Treatment of Limb Fracture and the Effect of Operative Success Rate and Postoperative Recovery Time

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.

A dynamic crash recovery scheme for distributed real-time database systems

Recovery performance in the event of failures is very important for distributed real-time database systems. This paper presents a time-cognizant logging-based crash recovery scheme （TCLCRS） that aims at distributed real-time databases, which adopts a main memory database as its ground support. In our scheme, each site maintains a real-time log for local transactions and the subtransactions, which execute at the site, and execte local checkpointing independently. Log records are stored in non-volatile high- speed store, which is divided into four different partitions based on transaction classes. During restart recovery after a site crash, partitioned crash recovery strategy is adopted to ensure that the site can be brought up before the entire local secondary database is reloaded in main memory. The partitioned crash recovery strategy not only guarantees the internal consistency to be recovered, but also guarantee the temporal consistency and recovery of the sates of physical world influenced by uncommitted transactions. Combined with two- phase commit protocol, TCLCRS can guarantee failure atomicity of distributed real-time transactions.

Sparse Recovery of Linear Time-Varying Channel in OFDM System

In order to improve the performance of linear time-varying（LTV）channel estimation,based on the sparsity of channel taps in time domain,a sparse recovery method of LTV channel in orthogonal frequency division multiplexing（OFDM）system is proposed.Firstly,based on the compressive sensing theory,the average of the channel taps over one symbol duration in the LTV channel model is estimated.Secondly,in order to deal with the inter-carrier interference（ICI）,the group-pilot design criterion is used based on the minimization of mutual coherence of the measurement.Finally,an efficient pilot pattern optimization algorithm is proposed by a dual layer loops iteration.The simulation results show that the new method uses less pilots,has a smaller bit error ratio（BER）,and greater ability to deal with Doppler frequency shift than the traditional method does.

Effects of the Ice Bath Time after Heat Shock and the Incubation Time on the Efficiency of Chemical Transformation Method

[Objective] The aim of the research was to study the effect of the ice bath time after heat shock and the incubation time on the transformation efficacy,and to establish a simple and quick transformation method.[Method]Competent cells were prepared with two buffer solutions;with the ice bath time after heat shock and the recovery time as the variables,the relationship between these two factors and transformation efficacy was studied.[Result]The transformation efficacy was the best when the ice bath time was 2 min and the recovery time was 30 or 40 min;when the ice bath time and the recovery time was 0 min,a certain amount of transformants still could be obtained.[Conclusion]The ice bath time after heat shock and the recovery time had certain impact on transformation efficacy,but they were not the decisive factors.Therefore,in the general transformation experiment,these two steps could be omitted.

区域医疗系统抗震韧性综述

韧性作为一种新的灾害风险管理理念,已成为防灾减灾领域的研究热点,考虑到医疗系统在城市运行和灾后救援中的重要作用,在地震期间和之后,区域医疗系统应该具有足够的韧性,并提供连续的医疗服务。如何综合考虑区域范围内多家医院和交通系统的安全性、应急响应能力、多系统的整合与协作,有效评估区域医疗系统的抗震韧性水平,并提出科学的改进建议,对建设韧性城乡具有重要的理论意义。本文通过梳理国内外文献,阐明了区域医疗系统韧性的概念和内涵,总结了地震后短期应急和长期修复两个阶段韧性评估的重点,归纳了现有区域医疗系统韧性的评估框架,从医院集群系统、面向医疗的交通系统、应急医疗服务系统和医疗-交通耦合系统4个方面阐述了现有评估方法。区域医疗系统韧性的研究旨在提高其面对灾害时的抵抗性、短期适应性和长期恢复性,这些研究对于满足紧急和日常的医疗需求以及指导灾后恢复具有重要意义。目前区域医疗系统抗震韧性的研究取得了一些进展,但仍然存在一些挑战,本文最后展望了未来的研究方向。

Oscillation in Response and Recovery Properties of SnO_2 Gas Sensor

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.

Source Timing Recovery of Constant-bit-rate(CBR) Services in ATM Networks

Asynchronous Transfer Mode(ATM)technique is regarded as an efficient approach forthe integration of diverse types of services in Broadband Integrated Services Digital Network(B-ISDN).The Asynchronous-Time-Division(ATD)Statistical Multiplexing and FastPacket Switching in ATM networks bring serious uncertainty to the end-to-end Cell DelayVariation(CDV)of the CBR traffic(e.g.voice,audio,CBR video,etc.)and cause troublesfor the Source Timing Recovery(STR)of CBR services.This paper discusses the originsand features of the CDV,two STR implementation methods proposed by the InternationalTelecommunication Union(ITU),and an optimal STR scheme with a Digital-to-AnalogConverter(DAC)based Phase-Locked Loop(PLL).

中性点柔性接地配电网故障相恢复电压暂态时域特征分析

配电网接地故障过零熄弧后的电压暂态恢复特性决定了系统过电压水平及电弧重燃特性,目前,中性点柔性接地配电网故障熄弧后暂态恢复电压变化机理尚不明确,为此建立柔性接地配电网接地故障暂态等值电路,理论解析故障过零熄弧后故障恢复电压的时域表达式。在此基础上,对比分析配电网谐振接地与柔性接地方式下,系统参数变化对故障相恢复电压暂态峰值与恢复速度的影响,揭示暂态时间尺度下故障相恢复电压特征随注入零序电流值与电流注入时机的变化规律,阐明通过中性点注入可控零序电流抑制故障暂态过电压的机理。在PSCAD/EMTDC仿真环境与10 kV真型配电网实验场中模拟各种运行和故障工况,仿真与真型实验结果均验证柔性接地配电网故障相恢复电压时域解析特征与变化规律的正确性。

Assessing building’s post-earthquake functional recovery accounting for utility system disruption

Experience from past earthquakes has demonstrated the need to account for design goals beyond safety,known as functional recovery objectives,in the interest of community resilience.Frameworks have been proposed in the literature to assess the post-earthquake functional recovery of a building,but without accounting for utility systems’disruption,which may be a key contributor to determining when a building is functional.This paper integrates a previously proposed probabilistic method for estimating the post-earthquake restoration of critical utility services with an individual building’s functional recovery assessment framework.The integration was performed by incorporating utilities into the building system fault trees embedded into a functional recovery framework for various building occupancies(residential and commercial office buildings).Once incorporated,the results are used to interrogate the functional recovery of a reinforced concrete building,and the recovery time results were presented for seven cases investigating contributing factors in the functional recovery results including the number of crews available for lifeline restoration,the effect of low-quality service on meeting tenant requirements for elevators,heating ventilation and air conditioning(HVAC),plumbing and electrical systems,consideration of fire watch,the effect of building seismic retrofit,as well as different cases of fragility functions for the lifeline systems.Results showed that utility systems’disruption does not have a significant impact on the recoccupancy of a building because only one utility-dependent building system(fire suppression)is needed for the building’s safety.Unlike reoccupancy,utility systems are significant for functional recovery,mainly at moderate hazard levels because,at these levels,lifeline networks could be damaged without significant building damage,such that the lifeline systems restoration governs.Buildings with more restrictive tenant requirements are more sensitive to tenant disruptions.

低渗砂岩油田CO_(2)驱化学机理及提高采收率研究

针对低渗砂岩油藏进行了CO_(2)驱开发技术研究,分析了CO_(2)驱油化学机理及主要影响因素。基于目标油藏流体特征进行了PVT拟合,确定其CO_(2)驱最小混相压力,明确了不同压力及注入时机对CO_(2)驱采收率、气油比、含水率及驱动压差等的影响规律,探究了CO_(2)泡沫驱在提高采收率方面的效用。结果表明:24.5 MPa为目标区域CO_(2)驱的最小混相压力,采收率会随着压力的升高而增加,28 MPa时CO_(2)驱提高采收率可达30.57%。气体突破时间、总采收率与CO_(2)注入时机密切相关,CO_(2)注入越早,越有利于采收率的提高,出口含水率为60%时注入可提高采收率39.13%。CO_(2)泡沫驱可以在一定程度上起到提高采收率的效用。

Progress in satellite gravity recovery from implemented CHAMP,GRACE and GOCE and future GRACE Follow-On missions

Firstly, the Earth＇s gravitational field from the past Challenging Minisatellite Payload （CHAMP） mission is determined using the energy conservation principle, the combined error model of the cumulative geoid height influenced by three instrument errors from the current Gravity Recovery and Climate Experiment （GRACE） and future GRACE Follow-On missions is established based on the semi-analytical method, and the Earth＇s gravitational field from the executed Gravity Field and Steady-State Ocean Circulation Explorer （GOCE） mission is recovered by the space-time-wise approach. Secondly, the cumulative geoid height errors are 1.727 × 10^-1 m, 1.839 × 10^-1 m and 9.025 × 10^ -2 m at degrees 70,120 and 250 from the implemented three-stage satellite gravity missions consisting of CHAMP, GRACE and GOCE, which preferably accord with those from the existing earth gravity field models involving EIGEN-CHAMP03S, EICEN-GRACE02S and GO_CONS GCF 2 DIR R1. The cumulative geoid height error is 6.847 × 10 ^-2 m at degree 250 from the future GRACE Follow-On mission. Finally, the complementarity among the four-stage satellite gravity missions including CHAMP, GRACE, GOCE and GRACE Follow-On is demonstrated contrastively.

Speech Signal Recovery Based on Source Separation and Noise Suppression

In this paper, a speech signal recovery algorithm is presented for a personalized voice command automatic recognition system in vehicle and restaurant environments. This novel algorithm is able to separate a mixed speech source from multiple speakers, detect presence/absence of speakers by tracking the higher magnitude portion of speech power spectrum and adaptively suppress noises. An automatic speech recognition (ASR) process to deal with the multi-speaker task is designed and implemented. Evaluation tests have been carried out by using the speech da- tabase NOIZEUS and the experimental results show that the proposed algorithm achieves impressive performance improvements.

GRACE time-varying gravity field solutions based on PANDA software

The conventional dynamic approach for gravity filed modelling has been implemented in the PANDA(Position and Navigation Data Analyst) software. A variant of the so-called ’two-step’ method for gravity field modelling is adopted for this purpose, where the GRACE(Gravity Recovery and Climate Experiment)orbits are derived from the GPS(Global Positioning System) data in a first step followed by a simultaneous determination of dynamic orbit and gravity filed from the GPS-derived orbits and K-band rangerate measurements in a second step. In this way, the monthly gravity field solutions complete to degree and order 96 are produced for the period Jan. 2005 to Dec. 2010. Their performance is assessed by comparing them with the official solutions, i.e., CSR RL05, GFZ RL05 a and JPL RL05. A comparison in the spectral domain in terms of geoid heights reveals that the obtained solutions present the smallest degree amplitudes at degree 30-75. A further analysis of mass changes in the spatial domain demonstrates that the main signals observed from the obtained solutions are in great agreement with those from the official solutions. Remarkably, the correlation coefficients of mass changes in large river basins from the official solutions with respect to those from the obtained solutions are all above 0.97. These results demonstrate that the obtained solutions are comparable to the official solutions.