Physical and numerical investigations of target stratum selection for ground hydraulic fracturing of multiple hard roofs

Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective control.Physical experiments are conducted based on engineering properties to simulate the gradual collapse of the roof during longwall top coal caving(LTCC).A numerical model is established using the material point method(MPM)and the strain-softening damage constitutive model according to the structure of the physical model.Numerical simulations are conducted to analyze the LTCC process under different hard roofs for ground hydraulic fracturing.The results show that ground hydraulic fracturing releases the energy and stress of the target stratum,resulting in a substantial lag in the fracturing of the overburden before collapse occurs in the hydraulic fracturing stratum.Ground hydraulic fracturing of a low hard roof reduces the lag effect of hydraulic fractures,dissipates the energy consumed by the fracture of the hard roof,and reduces the abutment stress.Therefore,it is advisable to prioritize the selection of the lower hard roof as the target stratum.

Thinking Out-of-Box in Addressing Communication and Service Delivery Challenges: Use of a Traditional Communication Method for Improving Immunization Coverage in Remote Rural Hard-to-Reach Areas of India

Sirmaur district in the state of Himachal Pradesh in India is a hard-to-reach area situated in the western Himalayas having an extreme landscape with snow-laden mountains and extensive river systems that makes the delivery of immunization services extremely challenging. Vaccinators needed a long walk through the hilly terrain to reach outreach sites. Community mobilizers were unable to go house to house to inform the caregivers to bring children to the site for vaccination. Caregivers were unaware when the vaccinators arrive at the site. As a result, many children missed vaccination or were not vaccinated timely. Age-appropriate vaccination coverage (according to national immunization schedule) in the Sirmaur district was the lowest in the state. Thinking out-of-box to address the communication barriers with the caregivers, the traditional drum beating was used, for the first time in India, in two blocks of the Sirmaur district (Rajpura and Shillai). The initiative was planned and implemented by the district health system with the support of the local community leaders. An exit interview was conducted to know the reach of the drum beating to caregivers, and a baseline and end line household survey was conducted to know the outcome of the initiative on age-appropriate vaccination coverage. Analysis of exit interviews data indicated a very high reach of a drum beating to the caregivers;more than 97% of caregivers in Rajpura and 100% in Shillai heard drum beating, and almost 95% of caregivers in Rajpura and 98% in Shillai knew the purpose of drum beating. Analysis of immunization data from baseline and end line surveys showed improvement in age-appropriate vaccination coverage for all vaccines in Rajpura (by 2.2% for BCG, 15.3% for Pentavalent 1, 14.9% for Pentavalent 2, 14.1% for Pentavalent 3, and 6.5% for Measles/MR). In Shillai, age-appropriate vaccination coverage improved for Pentavalent 1 (by 3.4%), Pentavalent 2 (by 5%) and Measles/MR (by 1.7%). In addition, dropout rates were reduced in both the blocks, particularly in Rajpura Pentavalent 1 to Measles dropout rate was reduced by 13.5%. Both health workers and community leaders had positive perceptions of the drum beating initiative. However, another important lesson learned from the initiative was that both the access and demand-side barriers need to be addressed for the desired improvement of age-appropriate immunization coverage. In Shillai, there was lower coverage improvement and a reduction in dropout rates attributed to vacant positions of vaccinators that caused an issue with access to immunization services to people.

Current Status and Correlates of Modern Family Planning Utilization in Hard to Reach Ethnic Minorities: The Case of Gumuz, Northwest Ethiopia

Cognizant of multifaceted challenge of unwanted pregnancy, Ethiopia strives to increase utiliza-tion of modern family planning across the nation. Therefore, update on the current status of family planning utilization especially in hard to reach ethnic minorities is critical. The objective of this study was to assess level, and correlates of modern contraceptive utilization in a hard to reach ethnic minorities. A community based study was conducted in Dangur District, Beneshangul Gumuz Regional State July, 2013. A total of 530 married women were included in the study. Structured questionnaire was data collection tool. Data was analysed using SPSS version 20 for windows. Possible association and their strength were measured using odds ratio at 95% CI. Family planning utilization was 18.7% while nearly 27% of study participants had ever used family planning methods. The following variables were predictors of family planning utilization: number of alive children [AOR: 3.31, 95% CI (1.41 - 7.20)], good knowledge [AOR: 2.18, 95% CI (1.35 - 3.52)] and positive attitude [AOR: 1.58, 95% CI (1.03 - 2.50)]. The most outstanding finding of this study was that more than 80% of study participants still believe that many children means high income, and nearly 60% of them believe that family planning utilization decreases confidence among couples. This study witnessed how successful Ethiopia is in addressing reproductive health service inequalities in hard to reach communities. However, misconceptions surrounding family planning, and culture associated desire to have large family size should be addressed in a culture sensitive manner so that this success would further bear fruits.

Adding Sputum Collection and Transportation Services for Early Identification TB Cases in Hard-to-Reach Difficult Terrain—Will It Help?

A community engagement project was designed and implemented to reach 10.6 million population in 13 districts of Uttarakhand state—India, to identify presumptive TB patients (PTBPs) and link to free diagnostics services, either through referral or sputum collection and transportation (SCT). The objective of this study is to determine additional yield of TB patients achieved by providing SCT services in comparison to referrals of PTBPs identified in hard-to-reach areas. This was before and after comparative study conducted between April-June 2014 (2Q2014-before) to July-September 2014 (3Q2014-after). SCT was advised for all PTBPs identified from community level interventions between July-September 2014 (3Q2014-after). In 3Q2014, additional 279 (34%) PTBPs were examined in the microscopy centre with an additional 36 (51%) new smear positive (NSP) patient diagnosed. A total of 46 NSP (128%) were contributed by SCT alone. Higher proportion (94%) of TB patients was initiated on treatment in 3Q2014 in comparison to 2Q2014 (91%). SCT as a strategy for early case detection in hard-to-reach difficult terrain yields positive results in comparison to mere referral of PTBPs.

Does Missing Data in Studies of Hard-to-Reach Populations Bias Results? Not Necessarily

Missing data are always an issue in community-based longitudinal studies, calling into question the representativeness of samples and bias in conclusions, the research has generated. This may be due to the difficulty of implementing random sampling procedures in these studies and/or the inherent difficulty in sampling hard-to-reach segments of the population being studied. In fact, the ability to accurately study hard-to-reach populations in light of potential bias created by missing data remains an open question. In this study, missing data are defined as both failure to interview potential research participants identified in the sampling frame and failure to retain enrolled research participants longitudinally. Using the sample from the Mobile Youth Survey, a multiple-cohort, longitudinal study of adolescents living in highly impoverished neighborhoods in Mobile, Alabama, we examined sample representativeness and dropout to determine whether missing data led to a nonrepresentative, and therefore, biased sample. Results indicate that even though random procedures are not strictly used to draw the sample, (a) the sample appears to be largely representative of the population that was studied, and (b) attrition is largely uncorrelated with characteristics of those who dropped out. This suggests that it is possible to study with validity hard-to reach populations in community settings.

Effective depth-of-penetration range due to hardness variation for different lots of nominally identical target material

The effect of small variations of target hardness on the depth of penetration for nominally identical target material has not been addressed systematically in publications yet and is often neglected. An investigation of this issue for laboratory-scale long rod projectiles penetrating into semi-infinite rolled-homogeneous-armor steel targets was conducted. The tungsten-heavy-alloy penetrators were of length 90 mm and diameter6 mm. Five lots of armor steel with a nominal hardness range of 280–330 BHN provided material for the targets. The pursued approach consisted of hardness testing of the targets, in total 17 ballistic experiments at velocities in between 1250 m/s and 1780 m/s and data analysis.A linear regression analysis of penetration vs. hardness shows that a target hardness increase within the given range of 280–330 BHN may result in a reduction of penetration depth of about 5.8 mm at constant velocity. This is equal to a change of-12% at an impact velocity of 1250 m/s. A multiple linear regression analysis included also the influence of yaw angle and impact velocity. It shows that small yaw angles and slight variations of impact velocities provide a smaller variation of the semi-infinite penetration depths than a variation of target hardness within a typical specification span of 50 BHN. For such a span a change in penetration of approximately-4.8 mm due to hardness variation is found, whereas 1°of yaw angle or-10 m/s of velocity variation gives a change of about-1.0 mm respectively-0.9 mm. For the given example, the overwhelming part of the variation is to be attributed to hardness effects – 4.8 mm out of 5.8 mm(83%). For nominally identical target material the target hardness thus influences the ballistic test results more severely than the typical scatter in impact conditions.

Improvement Properties of the Cutting Tools Using Technical Plasma Treatment

In spite of the considerable progress made in the domain of the sciences of materials, cutting tools subjected to an intense abrasive wear and a very high temperature of edge. They record during their use an reduced working life. The operations of machining on lathe are regularly stopped for replacing these tools, which influences enormously the production process. Indeed, the search the new materials of substitution, remain a domain very coveted, owing to the fact, it belongs to one stake very significant industrial, in particular, in the mechanical domain and its varied sectors. The recourse to the thermal treatments traditional, limiting in an interval, reduces the wear and the excessive consumption of these cutting tools, but the principal concern of the experts and researchers, in the domain of the mechanical engineering, remain posed. The goal of this study is the introduction of the technique of plasmas, as physical phenomenon, for making material of coating at base of titanium nitrides doped at iron, at the different concentrations. To this objective, one magnetron sputtering with plasma was used for the realization of the coatings deposed on the active parts of the cutting tools. During the experimentation, it was noted that the cutting tools which are treated by plasma, subjected to the machining operations on lathe and the hardness tests, presents one improvement of their hardness and a remarkable increase in their lifespan.

MOTION QUALITY EVALUATION OF TARGET-REACHING MOVEMENT OF INDEX FINGER

ms paper proposes a set of objective and quantitative human motion evaluation indices, among Which the index of difficulty and index of performance are introduced as the general indices for the quality measure of 2-D target-to-talget movement. As an example, the target-reaching movement of index finger, which is a basic functional action of index finger in the daily life of hUman beings, were experimentally investigated. In the experiment five healthy male subjects were asked to perform three target-reaching movement tasks Which have different indices of difficulty. All movements were recorded by a 3-D motion analysis system. Later, their motion qualities were measured with these evaluation metrics. The results showed that these indices are reasonable and have potential applications to biomedical engineering.

侵彻弹体过载信号特性与处理技术研究进展

侵彻弹体过载信号是反映侵彻物理过程的关键信号,可分为刚体减速度、弹体结构响应、连接结构响应和传感器噪声4种成分。介绍了4种成分的来源和各自特点,讨论了弹体结构响应和传感器相关信号各自的建模和评估方法。整理了针对过载信号进行分析处理的若干方法,比较了各种方法的精确性、自适应性、实时性和适用范围。对于过载信号处理实时性需求、重构手段、刚体减速度在复杂侵彻环境下的形式以及高速侵彻对过载信号分析处理带来的挑战展开了讨论。针对侵彻弹体过载信号研究现状,总结了存在的问题以及未来可能的研究方向。

基于DnCNN 的侵彻过载时频去噪方法

目的提高从侵彻过载中准确估计刚体过载信号的能力。方法提出一种基于前馈去噪卷积神经网络(DnCNN)的侵彻过载时频去噪方法,该方法首先应用短时傅里叶变换(STFT)提取侵彻过载信号的时频图像,使DnCNN能够充分利用时频图像信息,估计出刚体过载时频图像。最后,通过逆STFT将时频图像转换回时域,得到估计的刚体过载信号。结果在5-Fold交叉验证中,所提方法在测试集上的平均绝对误差(MAE)为0.968%,Pearson相关系数(r)为90.35%。与低通滤波、总体经验模态分解(EEMD)和小波变换方法相比,所提方法的平均MAE分别降低了1.82%、1.00%、0.75%,平均相关系数r值分别提高了47.81%、17.48%、22.93%。结论所提方法可以从侵彻过载中准确估计出刚体过载信号,在去噪能力上优于低通滤波、EEMD和小波变换方法,且在去噪过程中,无需调整参数,能够自动完成去噪任务。

“软硬兼设”系统的Topsis综合评价方法

把“软硬兼设”系统的软指标和硬指标分成两个不同的指标体系,对软指标体系的量化结果视为一个区间数矩阵,利用Topsis方法,把软指标与硬指标结合起来进行综合评价,并用以选择优秀农业科技带头人.参5。

汉江中下游重要支流目标生态流量分期控制研究

为有效推进河湖生态流量保障体系建设,采用Qp法、Tennant法、近10 a最枯月法、频率曲线法等方法计算分析确定了汉江中下游重要支流控制断面基本生态流量,采用适配法确定各断面生态流量分月泄放目标。研究表明:(1)汉江中下游重要支流控制断面的基本生态流量为1.16~7.50 m^(3)/s,占年均流量的5%~15%。除南河谷城断面受金盆沟电站发电引水导致满足度偏低外,其他断面满足度均高于90%,可作为生态流量管控依据。(2)各断面生存流量分月控制目标为1.16~55.00 m^(3)/s,年泄放量占年均径流量的20%,月均满足度可达80%以上。研究成果可为健全法规体系、强化工程生态调度、汉江流域水资源保护及监督管理提供参考依据。

穿越多种典型地层的跨海超大直径泥水盾构选型及针对性设计——以青岛胶州湾第二海底隧道为例

为缓解海底隧道盾构段施工中存在的关键问题,以青岛胶州湾第二海底隧道TJ-06标段为实际工程背景,针对“深蓝号”超大直径泥水平衡式盾构长距离、高水压穿越上软下硬土岩复合地层、全断面凝灰岩、断层破碎带、全断面花岗岩时的刀盘刀具磨损、刀具破岩能力不足、泥水舱滞排、刀盘泥饼堵塞和盾尾密封失效与主驱动密封失效等关键问题与难点进行针对性设计与研究,采取减小刀间距、优化刀具布置与形式、采用大直径短螺旋后接颚式破碎机排渣模式、加强并优化刀盘与泥水舱的冲刷等设计方案,实现了降低能耗、减少刀具损坏、缓解泥水舱滞排、提高施工效率,并极大地确保了施工安全的实施效果。

硬目标侵彻起爆控制技术研究现状及展望

为进一步推动硬目标侵彻起爆控制技术发展,按照硬目标侵彻起爆控制过程,综述了信号感知、信号处理与起爆控制方法的发展现状。分析侵彻过载信号组成、特征、响应传递的理论成果,总结基于过载时频特征的混叠信号处理、特征提取和特征强化方法,概述新型探测器件、滤波材料和自适应算法及数值仿真的研究现状,揭示了侵彻过载信号的复杂性和目前起爆控制技术的局限性。为满足侵彻弹药持续发展需求,应掌握弹体结构、目标特性、侵彻工况约束下过载特征变化规律,探究多物理场信号产生的机理,研究复合传感、信息融合及快速处理方法,制定基于模型驱动的起爆控制策略,形成适应范围更广泛的起爆控制方法。

Kiosk: An Innovative Client Centric Approach to Tuberculosis Prevention and Care

Kiosk is a client centric drop-in centre for TB information and services established in urban and peri-urban (slum) settings to provide outreach services under project Axshya. The main objective of the study was to demonstrate the efficacy and feasibility of scaling-up of the model to provide TB services. The assessment was carried out with the help of project recording and reporting formats used to document the information and services provided in the Kiosk from April 2016 to March 2017. The results from retrospective data analysis for services provided at 20 kiosks benefited 16,871 clients;of these 11,252 (66.7%), 1339 (7.9%), 848 (5%), 2911 (17.2%), (1.4%), 273 (1.6%) benefited with TB information, Flexi-DOT, sputum-collection-transportation (SCT), counselling, and domiciliary care respectively. Through active case finding (ACF);126,893 households were visited and 3593 presumptive-TB-patients received SCT services. A total of 329 TB patients were identified and linked to treatment services of national TB programme. “Kiosk” as a client centric approach would be a novel concept to ensure TB information, TB related services and contribute to ongoing efforts of TB case finding.

带有横梁结构的多层目标侵彻过载特征

针对当前对带有横梁结构多层目标侵彻过载认知不足,未开展相关测试的情况,通过建立不带有横梁结构的多层目标侵彻动力学模型,利用实测数据验模后进一步开展带有横梁多层目标的侵彻动力学数值计算,计算得到带有横梁结构多层目标的侵彻过载。经过对过载的峰值、持续时间以及粘连度指标分析,得到带有横梁结构多层目标的侵彻过载首层峰值增加了63.67%,过载持续时间增加了34.95%,粘连度增加了43.18%。研究结果为侵彻带横梁结构多层目标的准确计层提供了支撑。

高速侵彻战斗部终点弹道和引信过载特征

针对高速侵彻弹药打击地面多层建筑与深埋高价值硬目标时,引信信号识别不准的问题,建立包含战斗部外壳、炸药、引战结构、引信和目标靶板的有限元仿真模型,分析战斗部终点弹道特性、混凝土靶板侵彻破坏形态和引信动态过载特征,研究战斗部穿靶历程和战斗部速度变化、引信过载的时空对应规律。研究表明战斗部高速侵彻多层混凝土靶板在靶板上形成明显隧道区,战斗部速度呈现出显著的阶梯降低特征,在弹尖碰靶至卵型部完全入靶区间战斗部速度迅速降低,随后保持相对稳定。引信动态过载呈现高频振荡特征,在卵型部完全入靶到弹尾离靶的前1/4区间时刻处出现过载峰值。战斗部高速侵彻混凝土厚靶在厚靶上进行开坑和形成隧道区,弹尖碰靶至弹尖出靶区间战斗部速度呈现线性下降,引信过载峰值出现在弹尾入靶时刻。

供水管道水平定向钻穿越航道关键技术研究——以闽江水平定向钻穿越工程为例

为解决福州市琅岐岛供水不足问题而建设的塘坂引水工程琅岐支线(马尾段)供水管道,横跨穿越闽江航道,该管道内径为1 200 mm,长度为1 934 m,管材采用Q345B钢管。为减少该工程施工对现有地面设施的破坏并保证闽江主航路畅通,采用水平定向钻穿越施工法进行施工。本工程穿越地层为岩石与淤泥质黏土软硬交替地层,采用我国自主研发的新型2 000 t级电驱动水平定向钻机,应用新型的KY-100水平定向钻磁靶导向定位系统,并采用国际先进的双钻机对接穿越施工工艺,确保工程顺利实施;同时为了克服该工程穿越地层复杂、人工磁场铺设困难、穿越距离长、入出土点易冒浆等一系列工程技术难题,采取了双层套管、壁钩打捞及套洗钻具解卡等技术手段对钻杆弯曲、断裂等孔内事故进行了处理,提高了施工工效,减小了定向钻施工对地面设施和环境的影响。该相关技术经验可为类似工程的安全施工提供数据和技术支撑。

长杆高速侵彻下装甲钢靶的等效强度

装甲钢是复合装甲的主要组分之一,针对其抗长杆弹高速侵彻等效强度不明的问题,建立了三维SPH-FEM耦合模型。在验证模型可靠性的基础上,开展钨合金长杆弹在1 000~1 800 m/s初速度范围内侵彻半无限300~600 HBW装甲钢的仿真研究,基于侵彻阻力和Walker-Anderson(W-A)模型对高应变率-绝热工况下靶钢的等效强度进行探索。研究结果表明:侵彻过程分为初始瞬态、准定常和剩余侵彻3个阶段,W-A模型在大部分工况下可准确计算侵彻深度和准定常段头尾速度;准定常阶段杆体直径与靶体等效强度近似保持恒定,侵彻阻力可由Poncelet公式描述。基于以上分析建立装甲钢等效强度-硬度非线性换算模型,结合W-A模型能准确预测长杆弹对半无限靶的侵彻深度。此模型表明等效强度与硬度正相关,但热软化的增强与应变率强化的减弱使等效强度的增速逐渐放缓。

基于难样本挖掘与混合注意力机制的目标跟踪算法

在SiamFC目标跟踪算法的基础上,提出一种基于难样本挖掘和混合注意力机制的目标跟踪算法。首先,为了改善训练样本的数据分布情况,将图像自身边缘信息填充训练样本尺寸不足的区域来增强背景干扰信息;其次,在模板分支加入残差连接来对目标从不同层级进行特征表达;然后,在搜索分支采用混合注意力模块充分地提取特征信息;最后,使用深度可分离卷积降低模型复杂度。实验结果表明本文算法在遮挡、光照、旋转等复杂场景下具有良好的表现。