Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

Expanding the liver donor pool worldwide with hepatitis C infected livers, is it the time?

Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT candidates on the waitlist remains unchanged due to an imbalance between donor organ supply and the demand which increases the waitlist time and mortality.Living donor liver transplant had a great role in increasing the donor pool and shortened waitlist time for LT candidates.Nevertheless,further strategies can be implemented to increase the pool of potential donors in deceased donor LT,such as reducing the rate of organ discards.Utilizing hepatitis C virus(HCV)seropositive liver grafts is one of the expanded donor organ criteria.A yearly increase of hundreds of transplants is anticipated as a result of maximizing the utilization of HCV-positive organs for HCV-negative recipients.Direct-acting antiviral therapy's efficacy has revolutionized the treatment of HCV infection and the use of HCV-seropositive donors in transplantation.The American Society of Transplantation advises against performing transplants from HCV-infected liver donors(D+)into HCV-negative recipient(R-)unless under Institutional Review Board-approved study rules and with full informed consent of the knowledge gaps associated with such transplants.Proper selection of patients to be transplanted with HCV-infected grafts and confirming their access to direct-acting antivirals if needed is im-portant.National and international consensuses are needed to regulate this process to ensure the maximum benefit and the least adverse events.

U-Net Based Dual-Pooling Segmentation of Bone Metastases in Thoracic SPECT Bone Scintigrams

In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of distinct feature encoding and decoding stages, with dual-pooling modules employed in encoding stages to maintain the background information needed for bone scintigrams diagnosis. Both the DAC and RMP modules are utilized in the bottleneck layer to address the multi-scale problem of metastatic lesions. Experimental evaluations on 306 clinical SPECT data have demonstrated that the proposed method showcases a substantial improvement in both DSC and Recall scores by 3.28% and 6.55% compared the baseline. Exhaustive case studies illustrate the superiority of the methodology.

Experimental Investigation on Flame Characterization and Temperature Profile of Single/Multiple Pool Fire in Cross Wind

An experimental study was carried out to investigate the flame characterization and temperature profile for single and multiple pool fire with the influence of cross wind.There were 13 test cases in total,categorized into circle and rectangle fuel pans,with diameter(or equivalent diameter)ranged from 50 mm to 300 mm.Kerosene was used for the fuel of pool fire.Some K-type thermocouples were arranged around the flame to monitor the flame temperature,while the flame tilt angle was measured based on the photograph of flame for different case.Firstly,it can be found that there are three phases,including preheating,steady burning and extinguishing phase,during the flame evolution.The maximum temperature near the fuel surface is~1040 K,which is higher than that of flame plume(~600 K),in the steady burning phase of circle single pool fire(D=300 mm),while the average burning rate is~1.525 g/s.In addition,the burning rates of all cases were measured and compared with the current predicted method.Typically,the flame morphology of single/multiple pool fire at different cross wind speed(ranging from 0 to 3.5 m/s)was analyzed,and it is found that the results for single pool fire agree with Thomas model and AGA model well,which are not suitable for multiple pool fire.Finally,the temperature profile of different case was measured with various wind speed.

Experimental study on burning rate of small scale heptane pool fires

Burning characteristics of small scale thin-layer n-heptane pool fires were experimentally studied.Flame height,burning rate and fuel temperature distribution of pool fires with different diameters were measured.Fuel surface temperature and wall heat flux were analyzed.Four typical burning phases,which include pre-burning,quasi-steady state burning,boiling burning and decaying phases,are revealed based on the experimental data and phenomenological analysis.It is shown that flame height and burning rate of boiling burning phase are both significantly greater than those of quasi-steady state burning phase.Fuel surface temperature rises to boiling point rapidly in the early stage of pool fire,and then remains almost unchanged.Boiling burning will occur when the wall temperature is not less than the fuel boiling point.

Experimental Study on the Interaction of Fine Water Spray with Liquid Pool Fires

An experimental study of the interaction of a fine water spray with liquid pool fires was performed. Spatially resolved droplet size, velocity distributions, and volume flux of the fine water spray have been obtained in two types of pressure-atomized fine spray, using LDAIAPV technology. A method to correct for the presence of droplets is presented and used to determine the heat release rate using a cone calorimeter system, the effects of water spray application on the heat release rate for liquid pool fires were studied. It was found that the volume flux of the water spray is an important factor to determine the liquid pool fire behavior. For the current experimental conditions, the flame was enlarged when lower volume flux of water is used, and suppressed significantly when larger volumes of water are used. Two opposing mechanisms compete when water sprays are applied, which is more complex than the halon agents, such as 1301. The combustion enhancement becomes insignificant when water sprays with the proper characteristics such as adequate volume flux are applied to the diffusion flame in a confined space.

Experimental study on the interaction of fine water mist with solid pool fires

This paper describes experimental study of the interaction of fine water mists with solid pool fires. Fine water mist was generated by a single pressure nozzle and solid pool fires were produced from solid red pine or polymethyl methacrylate(PMMA). The LDV/APV system was em-ployed to determine the water mist characteristics. The water mist droplet sizes and velocities from the nozzle were measured under varying conditions and at different locations. The effects of solid type, water flow rate, and nozzle distance from the sample surface on extinguishments time were examined. At a given water flow rate, the extinguishment time is much longer for PMMA fires than for solid pine fires. The extinguishment time was found to decrease with increasing water flow rate. At very low water flow, the extinguishment time decreases when the nozzle is positioned further from the sample surface. On the contrary, at high water flow, the extinguishment time appears to be independent of the distance between the nozzle and the sample surface. The experimental re-sults show that flame extinguishments is due primarily to fuel surface cooling and wetting.

The Study of the Damage Laws of Pool Fires

ＴｈｅＳｔｕｄｙｏｆｔｈｅＤａｍａｇｅＬａｗｓｏｆＰｏｏｌＦｉｒｅｓ￥ＹｕＤｅｍｉｎｇ；ＦｅｎｇＣｈａｎｇｇｅｎ；ＺｅｎｇＱｉｎｇｘｕａｎ；ＧｕｏＸｉｎｙａ（Ｍｅｃｈａｎｉｃｓ＆ＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，ＢｅｉｊｉｎｇＩｎｓｔｉｔｕ...

Simulation of single bubble dynamic process in pool boiling process under microgravity based on phase field method

We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates.

Genotyping ex situ trees of Abies nebrodensis translocated from the original Sicilian population to enrich the gene pool

As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ex situ populations were planted with this gene pool:a seedling arboretum in Pieve Santo Stefano(PSS)and a small dendrological collection in Papiano(PAP),both originating from the Sicilian relict population.Here,using AFLP markers,we estimated the relatedness among the relocated genotypes of the three collections to check whether the three collections had suffi cient genetic variability to be considered as additional sources of variability to the original gene pool for the assisted migration strategy.High individual genetic variability was found in the collections;each plant had a diff erent genotype and was confi rmed to belong to its population of origin.PAP and PSS trees were shown to be only from the original population of A.nebrodensis species and were derived from a limited set of maternal fertile genotypes.Based on the Sicilian fi r population inventory,nursery production in Sicily,and structure clustering analysis,close genetic relationships among POM,PAP and several PSS trees(1–35)were evident.Similarly,the PSS group(36–78)was genetically close to tree 1 of POM and in a lesser proportion to plants 7 and 9 of POM.The sampling of seedlings used to form batches in the nursery might have infl uenced the structure of the resultant plantations.All genotypes will be useful for enriching the original gene pool.

Pooled Sputum for Xpert MTB/RIF Testing: A Cost-Saving Strategy in Mwanza, Tanzania

Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed the utility and cost-saving of pooled Xpert MTB/RIF testing strategy for the diagnosis of TB in Mwanza, Tanzania. Methods: Sputum samples from Presumptive TB patients were submitted to TB laboratory for routine diagnosis of TB using Xpert MTB/RIF. The TB results from the individual sputum samples were used as the reference standard and were concealed to the investigating laboratory technicians. The remainder of samples were collected serially and were pooled (5 samples per pool) for testing. The agreement of the results between individual sample testing against pooled sample testing and cost-savings was assessed. Results: A total of 250 sputum samples from presumptive TB patients were analyzed and 50 pools were made with each pool containing 5 samples. Of the 50 sputum pools made, Mycobacterium tuberculosis (MTB) was detected in 17 (34.0%) pools. Results from the individual sputum samples MTB/RIF testing were retrieved for all 250 samples and there were 28 (11.2%) samples in which MTB was detected whereas 222 (88.8%) samples had no MTB detected. Following re-analysis of positive pools, all 28 (100%) individual positive MTB samples were detected within the 17 positive pools, with 1 to 3 individual MTB positive samples per pool. The individual sputum samples were correctly identified by pooled sputum on Xpert MTB/RIF testing, with the sensitivity of 100% and specificity of 100%. Using pooling of sputum samples strategy, we saved 46.0% (115/250) of the cartridges. Conclusion: The pooled sputum testing strategy reduced cartridge costs by 46.0% and has the potential to increase the affordability of Xpert MTB/RIF testing in countries with limited resources, such as Tanzania.

Comparisons of Structured Surface Floors for Pool Boiling Enhancement at Low Heat Fluxes: Hands-On Learning Setup for Heat Transfer Classroom

Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. The pool boiling performance of water under atmospheric pressure of 1.025 bar is investigated by using several structured surfaces at heat fluxes of 28 and 35 kW/m2. Surfaces with holes, rectangular grooves, and mushroom fins are manufactured by an NC-controlled vertical milling machine. The heat flux versus excess temperature graph is plotted by using thermocouple measurements of water and base temperatures of the boiling vessel. The separation, rise, and growth of individual vapor bubbles from the surface during boiling were recorded with a digital camera. The results for the plain surface are compared to the Rohsenow correlation. The enhancement of heat transfer coefficient (h) ranged between 15% - 44.5% for all structured surfaces. The highest heat transfer coefficient enhancement is observed between 41% - 56.5% for holed surface-3 (405 holes) compared to the plain surface. The excess temperature dropped around 29% - 34% for holed surface-3 (405 holes) compared to the plain surface. The heat transfer coefficient increases as the spacing between channels or holes decreases. While the bubbles on holed and mushroomed surfaces were spherical, the bubbles on the flat and grooved surfaces were observed as formless. The suggested economical test design could be appropriate to keep students focused and participating in the classroom.

基于FDS的风扇舱双油池火温度变化特征

航空发动机燃油泄漏形成的油池火威胁发动机运行和飞机安全,为描述风扇舱内油池火复杂的物理传播过程,开展双油池火温度变化特征的研究。首先,基于火灾动力学模拟软件(FDS)建立CFM56-7B发动机风扇舱物理计算模型;然后,比较Trent 800发动机风扇舱单油池火温度计算值与试验值,验证网格独立性;最后,借助探测器和切片分析舱内双油池火的发展过程和温度变化特征。结果表明:双油池火温度在舱内环向上经历增加和振荡准稳态2个变化阶段,其变化幅度与探测器和油池的间距相关;油池火向左偏斜现象导致左半边温度较高;火焰在轴向上经历火羽流上浮、火焰开始融合、融合扩大和完全融合等阶段。

基于改进Faster R-CNN的热轧带钢表面缺陷检测

热轧带钢是钢铁行业的重要产品,其表面缺陷是影响产品质量的重要因素。针对传统缺陷检测算法存在的过程繁琐、精度不足和效率低下等问题,提出一种基于改进更快速区域卷积神经网络(faster region-based convolutional neural network,Faster R-CNN)的检测算法,实现对热轧带钢表面缺陷的高效、高精度检测。首先,采用特征相加的方法对底层细节特征和高层语义特征进行融合;然后,采用精准的感兴趣区域池化(precise region of interest pooling,Precise ROI Pooling)获取固定大小的特征向量,避免特征出现位置偏差;最后,利用均值偏移聚类算法对带钢数据集进行聚类,获得适用于热轧带钢表面缺陷检测的先验框尺寸。实验结果表明,所提算法在热轧带钢表面缺陷检测数据集上的平均精度均值达到了85.34%,检测速度为23.5帧/s,且鲁棒性良好,满足实际的工业检测需求。

高高原受限空间内小尺度油池火燃烧特性试验研究

为研究我国高高原地区的受限空间内液体燃料小尺度油池火燃烧特性,在高高原康定机场自主搭建受限空间内油池火的试验平台。共选取3类典型液体燃料(航空煤油、航空汽油、正庚烷)进行燃烧试验,测量火焰高度、火焰温度和烟气成分等变化规律,研究了高高原受限空间内小尺度油池火行为。研究发现:在高高原地区,正庚烷稳定燃烧阶段的平均火焰高度可以通过模型L/D=k+0.254Q^(2/5)/D表示,其中,火焰高度与压力之间的关系式为L/D~p^(-2/9)。3种燃料的火焰最高温度均超过600℃,而羽流轴线温升与火焰高度呈现-5/3的指数关系。产烟速率则表现出对环境压力的依赖性,其关系可表示为:v~p^(-1/3)。

辛空间的排列问题及具有容错能力的pooling设计的紧界

该文利用辛空间上的子空间构造了一类新的d^z析取矩阵,然后研究了如下排列问题:对于给定的整数m,r,s,v,d,q和辛空间F_q^(2v)中的一个(m,s)型子空间S,这里v+s≥m>r≥2s-1≥1,d≥2,q是一个素数的幂,作者从S中找到d个(m-1,s-1)型子空间H_1,…H_d,使包含在这些(m-1,s-1)型子空间中的(r,s-1)型子空间个数达到最大.然后利用这个排列的有关结论,给出了一类pooling设计的紧界.

Pool模式下基于报价的传输阻塞管理

对pool模式下的传输阻塞管理进行了研究。首先分析了社会福利最大化的传输阻塞管理方法的不足之处:报价曲线和成本曲线的差别使得模型中的优化目标难以实现,产生阻塞盈余。在此基础上,提出了基于报价的传输阻塞管理模型,算例分析表明,和最大化社会福利的阻塞管理方法相比,新方法能产生较多的市场交易量,且能消除阻塞盈余的产生,为电力市场下的阻塞管理提供了一条新思路。

基于DNA pooling技术的全基因组关联研究筛选主动脉夹层等位基因遗传位点

目的:筛选与主动脉夹层发病机制相关的遗传易感基因。方法:从主动脉夹层患者(150例)及对照组(250例)外周血白细胞提取基因组DNA,采用DNA Pooling为基础的Illumina Human660W-Quad芯片扫描,筛选与主动脉夹层发病相关的遗传易感基因。结果:(1)对照组女性数量明显多于病例组(P<0.01);年龄、吸烟、高血压、糖尿病人数无统计学差异(P>0.05)。(2)遗传变异位点SNPrs2298491(位于TBCEL基因),SNP rs6080720(位于BFSP1基因),SNP rs7653410(位于SNTN基因),SNP rs2345106(位于COLQ基因)和位于ABCA13基因上的SNPrs4024044可能与主动脉夹层的发病有关。结论:SNPsrs2298491,rs6080720,rs7653410,rs2345106和rs4024044可能是主动脉夹层发病机制相关遗传变异位点的一部分。

利用伪辛子空间构造的一类pooling设计及其纠错能力的紧界分析

利用伪辛空间上的子空间构造了一类新的dz-析取矩阵,证明了它的析取性,讨论了反映dz-析取矩阵纠错能力z值的紧界.

基于MSC Pool的软交换组网策略

随着软交换大规模投入使用,如何在兼顾网络资源、注重网络安全的基础上,有效简化网络扩容、合理配置MSC/MSC Server的容量及分担话务已经成为中国移动日益关注和重视的焦点。文章通过对MSC Pool技术原理、基本业务流程以及特点优势的介绍,由此引入基于MSC Pool的软交换组网策略,并就发展趋势、规划原则以及最终目标做了分别阐述和分析。