Analysis of inhibition of concrete steel-rebar corrosion by Na_2Cr_2O_7 concentrations:Implications for conflicting reports on inhibitor effectiveness

Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.

EFFECTIVE DIFFUSION AND EFFECTIVE DRAG COEFFICIENT OF A BROWNIAN PARTICLE IN A PERIODIC POTENTIAL

We study the stochastic motion of a Brownian particle driven by a constant force over a static periodic potential. We show that both the effective diffusion and the effective drag coefficient are mathematically well-defined and we derive analytic expressions for these two quantities. We then investigate the asymptotic behaviors of the effective diffusion and the effective drag coefficient, respectively, for small driving force and for large driving force. In the case of small driving force, the effective diffusion is reduced from its Brownian value by a factor that increases exponentially with the amplitude of the potential. The effective drag coefficient is increased by approximately the same factor. As a result, the Einstein relation between the diffusion coefficient and the drag coefficient is approximately valid when the driving force is small. For moderately large driving force, both the effective diffusion and the effective drag coefficient are increased from their Brownian values, and the Einstein relation breaks down. In the limit of very large driving force, both the effective diffusion and the effective drag coefficient converge to their Brownian values and the Einstein relation is once again valid.

Towards an Effective Communication in the Care of Patients with Long Term Disease in Kenya via Cybernetic—A Systematic Review

In this paper, to effectively treat chronic disorders and improve the standard of care, effective communication between patients and healthcare professionals was essential. The aim of the study was to review the literature on how good communication might improve treatment outcomes for Kenyan patients with chronic and terminal illnesses and to determine whether Cybernetic electronic communication can improve those outcomes even more. We uncovered the history of treatment outcomes for chronic and terminal diseases in this research study, both with and without communication at the core of the patient’s care plan. We discussed the importance of good communication in the treatment of patients with chronic and terminal illnesses and why it is a momentous endeavor comparable to medical diagnosis and treatment for the long-term health of patients. To locate pertinent material for the background literature study, we carried out a comprehensive literature search. Although the preliminary literature review was a continuation of the introduction research, it also highlighted the paucity of local Kenyan literature and suggested that improved communication might help patients with chronic and terminal illnesses have better treatment outcome. Methodology maintained the literature search, as a systematic literature review focused on core of the study, making separate sections of the same body necessary. This ensured that a methodological literature search section is as comprehensive as possible. We used an integrated PRISM model to limit a comprehensive literature search and a systematic literature review design as part of the overall process. Non-probability sampling and snowball approaches on literary papers over the previous 17 years were used in this arrangement. Since this was a multidisciplinary study, the four experts who also serve as authors were chosen from within their respective fields of expertise to design the study. They created search strategies, generated key words, looked up keywords in database engines, assessed the results of the literature using the PRISMA logical model, looked over successful literature, and triangulated their findings. The conclusions of the experts individually revealed a convergence of thoughts, beliefs, and practices across. The study concluded that even though there isn’t much research done in Kenya on the same subject;what is available illustrates how crucial good communication is for patients with chronic illnesses. The study’s findings also highlighted the positive effects of effective communication between patients and healthcare professionals on treatment plan adherence, patient satisfaction, and overall health outcomes. The results also noted that in order to improve patient care and outcome, Kenyan healthcare workers should underscore developing their communication skills. The study also found that the incorporation of cybernetics is crucial if a truly effective communication is required so as to enable centered care for patients with long-term diseases in Kenya. The goal of the Cybernetics is to activate genuinely effective communication in the care of Patients with long-term disease in Kenya. This study is organized to begin with an abstract, followed by keywords, an introduction, literature review, methodology, findings, discussion, and finally conclusions.

埋地燃气管道失效风险时间序列预测在常州市的应用

为研究常州市埋地燃气管道失效风险的时间效应,选取了影响其失效概率的4个主要因素,根据灰色模型GM(1,1)分析了各影响因素的时间效应,在此基础上将灰色模型与神经网络有机结合构建了灰色神经网络模型(GNNM),进而利用灰色神经网络模型分析了各因素影响下常州市埋地燃气管道综合失效概率的时间效应,然后借助失效概率转换函数将失效概率转换为预警失效概率,最后实现了对常州市埋地燃气管道2027年的失效风险预警。预警结果表明,2027年研究地区大部分区域的埋地燃气管道风险等级将进入较高风险,东南及东北的小部分区域风险将变为高风险,需要尽快采取相关措施抑制其失效风险的持续上升以及预防失效致灾事故的发生。

多天线半双工中继系统的隐蔽通信

基于译码转发中继探究了多天线半双工中继系统的隐蔽通信,即以装配有多天线的源节点分别在两个阶段中以迫零波束赋形(ZFB)和随机选择干扰(RSJ)的传输方案扰乱Willie检测,从而保护隐蔽信息的传输。首先,推导了Willie在两个阶段中的最优检测阈值和最小检测错误概率;其次,基于平均最小检测错误概率约束的情况下,推导、分析和优化了第一阶段源节点的发射功率和第二阶段中继节点的转发功率,并获取了各阶段的最大有效隐蔽速率;最后,根据各阶段的隐蔽性能指标,推导了系统总的传输中断概率和最大有效隐蔽速率。实验结果表明,当天线数量n≥3时,系统总的传输中断概率随着天线数量的增加而减小,并且系统总的最大有效隐蔽速率同第二阶段相同。

考虑停运概率熵和网架结构熵的电网关键线路辨识方法

线路停运概率对连锁故障的触发和演化具有重要影响。然而,现有关于电网线路停运概率分布均衡性的研究存在考虑不足的问题。文中结合复杂网络理论分析方法与熵理论,提出综合考虑停运概率熵和网架结构熵的电网关键线路辨识方法,旨在量化线路在电网运行状态和网络状态层面的综合影响力。首先,基于线路停运概率模型,提出了停运概率分布熵与停运概率变化熵指标,区分了线路潮流在正常值范围内、正常值与极限值之间和大于极限值3个状态对辨识结果的影响,克服了现有指标中对直接影响线路故障因素考虑欠缺的不足。其次,结合改进网架结构熵,提出了反映电网网架结构和运行状态的关键线路综合指标。然后,结合功率平衡策略,提出电网关键线路辨识方法。最后,基于改进网络效能指标对IEEE 39节点系统和IEEE 118节点系统进行仿真,验证了所提方法的可行性和正确性。

低轨增强对北斗量化信号载噪比的影响

为了评估频点兼容下低轨增强对北斗信号接收的影响,从而指导接收机设计,通过概率统计理论推导了低轨增强下北斗信号的量化效应和载噪比损耗模型,并通过蒙特卡罗仿真给出了1~6 bit量化位宽下北斗信号的载噪比损耗与前端增益以及低轨增强功率的关系,仿真与理论结果的一致性较好。实验结果表明,北斗信号最小载噪比损耗对应的最优前端增益与低轨增强功率无关,但最小载噪比衰减值会随着低轨信号功率的增强而增大,1~2 bit量化位宽下有明显的量化损耗,3 bit及以上量化位宽下北斗信号载噪比衰减特性基本一致。

储量不确定性分析中的参数优选与应用

概率法是进行储量不确定性分析的研究方法。目前常规方法是选取含油面积、有效厚度、孔隙度、含油饱和度等主要参数作为随机变量,运用容积法计算公式进行评估。研究以珠江口盆地海相砂岩油田为例,分析有效厚度和净毛比(Net Fo Gross,NTG)两个参数在概率法中的差异,发现选取有效厚度作为随机变量的常规方法在实际应用中存在一定的局限性。通过优化计算公式,选用净毛比作为主要参数进行评估,估算储量的数学期望(Pmean)与容积法估算储量的相对误差更小,储量概率分布曲线更为集中,估算结果可靠程度更高。

Frame length optimization for multi-antenna downlink systems based on delay-bound violation probability constraints

A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.

First-chance fission probability and presaddle nuclear dissipation

Dissipation retards fission, resulting in a drop in the first-chance fission probability of a fissioning nucleus with respect to its statistical model value. We use the Langevin model to compute the evolution of the drop(due to friction), P_(f0)^(drop), for the fissioning systems^(220)Th and ^(240)Cf with the presaddle friction strength(b). The firstchance fission probability is shown to depend sensitively on b, and the sensitivity is apparently greater than that of the total fission probability. We further find that although the total fission probability of heavy ^(240)Cf is insensitive to b, its first-chance fission probability is quite sensitive to b.These results suggest that, to strongly limit the presaddle friction strength, an optimal experimental avenue is to measure the first-chance fission probability of heavy fissioning nuclei.

A Class of Chaotic Sequences with Gauss Probability Distribution for Radar Mask Jamming

A simple generation approach for chaotic sequences with Gauss probability distribution is proposed. Theoretical analysis and simulation based on Logistic chaotic model show that the approach is feasible and effective. The distribution characteristics of the novel chaotic sequence are comparable to that of the standard normal distribution. Its mean and variance can be changed to the desired values. The novel sequences have also good randomness. The applications for radar mask jamming are analyzed.

Study on Quadratic Effect Assessment of Vulnerability of Military Aircraft Under Multiple Hits

Under the conditions of multiple hits and quadratic effects,the aircraft vulnerability assessment method is proposed by means of kill-tree diagram and state transition matrix.Four instances of the quadratic effects are investigated:non-redundant components to non-redundant components,non-redundant to redundant,redundant to non-redundant and redundant to redundant.The application of the proposed method to the calculation of quadratic effects is also studied.

考虑温度和时间双重影响的混凝土蠕变模型构建

为了研究温度对混凝土结构蠕变特性的影响,开展不同温度作用下混凝土三轴蠕变试验,分析了不同温度作用下混凝土结构的轴向蠕变特性。在温度作用下,混凝土的内部损伤与非均匀程度参数有关,建立非均匀程度参数与温度之间的关系;假定混凝土蠕变模型是关于温度和时间的函数,结合上述损伤变量和微元体强度分布概率模型,建立了考虑温度和时间双重影响的混凝土蠕变模型。基于最小二乘法和试验数据对模型的准确性进行验证,并采用西原模型对其优越性作进一步验证。结果表明:不同温度作用下蠕变损伤模型与试验数据的吻合度都较好,且相关性系数在0.95以上,说明了所建立模型的正确性;同时,该模型与试验数据的吻合度要优于西原模型,并且在描述加速蠕变方面具有一定的优越性。该理论模型为地下工程中混凝土支护结构的长期变形预测研究提供理论依据。

公路隧道地面效应对双火源火焰合并特性影响的试验研究

为研究自然通风隧道内发生双重火灾时地面效应对双火源火焰合并特性的影响,利用1:10小尺寸隧道模型开展了一系列试验。重点探究了双火源表面与隧道地面平齐时火源间距对火焰合并概率与火焰合并点高度的影响。结果表明:火灾烟气从隧道两端开口流出,由隧道两端补充进的新鲜空气产生的风速导致火源间距更大时火焰依然会发生互相倾斜,在间距足够大时,火焰倾斜角度约为10°。引入一个无量纲量表示火焰合并概率随着火源间距、热释放速率的改变而变化的规律。另外,将本文的试验数据与前人的工作做了比较,发现地面效应对隧道纵向布置的双火源火焰合并行为具有极大的促进作用。同时给出了火焰合并点高度与隧道高度的比值与改良后无量纲热释放速率的关系式。

基于F-J-M法的桥梁温度与地震作用效应组合研究

目前铁路桥梁设计逐渐由容许应力法向极限状态法转变,而《铁路桥涵设计规范(极限状态法)》(Q/CR 9300—2018)并未提及地震作用与温度等可变作用的联合作用,给高寒高烈度区桥梁结构抗震设计带来了较大困难。为了推进桥梁以更经济的抗力方式抵御外荷载作用,通过目标可靠度指标确定其最优地震设计状况荷载组合分项系数,从而对现行桥梁设计规范抗震设计进行优化。建立了高寒地区某桥温度作用效应概率模型,使用Ferry Borges荷载组合理论探究地震和环境温度作用的效应分布特征,并基于JC法和多灾害荷载系数设计法(MH-LRFD)建立地震、温度作用荷载系数的表达式。依托某桥梁工程实例分别探究了地震、温度以及两者共同作用下的桥梁的失效概率。研究结果表明:环境温度引起的桥梁温度内力响应、主要构件材料特性变异均能显著影响桥梁的失效概率;对于高寒大温差地区,现行规范忽略环境温度效应将显著低估桥梁在地震作用下的失效概率。本文提出的F-J-M(Ferry Borges+JC+MH-LRFD)方法计算地震、温度作用组合系数,可为高寒地区桥梁抗震设计提供必要理论依据。

考虑速度聚束效应的SAR海浪成像仿真方法

针对合成孔径雷达(SAR)海浪成像仿真技术对于速度聚束效应的考虑不充分,仿真数据无法准确反映实际SAR数据的问题,建立一种充分考虑速度聚束效应的SAR海浪成像仿真方法并进行了实验验证。计算了SAR图像强度的概率密度分布的仿真结果与理论结果之间的均方误差(MSE),在风速分别为5、10和15 m/s时,考虑速度聚束效应前、后比对结果的MSE分别为0.1012、0.1576、0.0556与0.0179、0.0314、0.0088。仿真结果表明,所提SAR海浪成像仿真方法有效提高了仿真数据的准确性,对SAR海浪成像的应用具有一定实用价值。

采用改进等价极值法的钢网架动力可靠性分析

为比较动力作用下航站楼钢网架结构可靠性的空间分布差异,基于等价极值原理中的极值(P),推导并改进了以逼近极值(ΔPi)为特征变量的结构失效概率计算方程。结合某机场航站楼钢网架优化案例,数值模拟分析了指廊钢屋盖在不同有效峰值加速度(effective peak acceleration,简称EPA)作用下的结构可靠性变化规律,总结了改进等价极值法在预测结构失效时的优越性。结果表明:利用改进等价极值法得到的结构失效概率上下界曲线能准确表征不同EPA作用下结构失效的“三阶段”变化趋势,且计算阈值区间随EPA增加而收敛,并在EPA大于0.22 g时趋于0;在结构设计优化指标满足规范要求时,改进等价极值法既能有效预测其可靠性变化趋势又具有较高预测精度;指廊结构区段内的支座节点失效概率与整体失效概率接近,EPA小于0.295 g时误差不超过4%,可通过监测代表节点实现结构整体可靠度监测。

岩溶典型区崩塌落石被动防护网失效概率模拟

贵州省位于我国西南地区,多山地丘陵,是典型的喀斯特地形地貌区,崩塌、滑坡等地质灾害频发。思南县小屯岩崩塌带上现存危岩体方量大,裂隙、凹岩腔、溶蚀孔洞等发育。为研究岩溶典型区崩塌落石被动防护网失效概率,通过高精度实景建模技术,构建崩塌带三维模型,进行崩塌落石运动过程模拟,根据现场调查、无人机航拍和数值模拟结果,选择合适的位置布设落石被动防护网。基于落石粒径大小识别,选取不同粒径大小的落石,进行落石被动防护网拦截效果模拟,计算落石被动防护网失效概率。结果表明:13种粒径落石突破概率各不相同,(0.25,2.25)m粒径落石拦截效果良好,但落石被动防护网拦截率不能达到百分之百;落石粒径大于2.25 m,被动防护网出现失效现象,故将2.25 m粒径的落石为小屯岩崩塌带下被动防护网的设计上限。根据计算,所有粒径落石经被动防护网拦截后的失效概率低于5%,属可接受范畴。研究成果为小屯岩崩塌带的落石防护措施提供了有力的参考依据,对保护岩溶地区山区人民的生命安全和财产安全具有重要意义。

基于LSTM_TCN模型的降雨型滑坡时间概率预测及气象预警建模

如果滑坡发生时间信息不完备则会导致滑坡与降雨时序关系错误,以至于降雨阈值模型精度偏低。以重庆市万州区1995-2015年所发生的降雨型滑坡为研究对象,将区内严重缺失历史滑坡时间信息的恒合乡作为验证区,提出了一种基于长短时记忆网络(LSTM)融合时域卷积网络(TCN)的模型方法。该方法通过模拟降雨型滑坡发生时间与降雨量间的非线性关系,重建降雨型滑坡事件在某日发生的时间概率。将重建时间信息后的滑坡事件进行了验证与筛选,应用于累积有效降雨量-降雨历时曲线的合理划分,构建了滑坡气象预警模型。结果表明,本方法所预测滑坡时间概率平均值达到90.33%,高于人工神经网络(ANN)(71.17%)、LSTM(72.75%)和TCN(86.91%)的概率。利用预测概率高于90%的滑坡,将验证区18个时间信息扩充至201个。基于扩充时间信息后的滑坡数据所构建的气象预警模型比仅利用历史滑坡事件具有更合理的预警分级,在严重警告级别上有效预警率提升了42.86%。结果说明该方法可弥补野外调查中灾害数据时间信息不足的问题,为降雨型滑坡气象预警工作提供数据支撑,由此提高气象预警准确率。

地震和滑坡链式灾害作用下连续梁桥结构易损性分析

目前桥梁结构抗多灾害研究主要集中在桥梁结构冲刷与主余震方面,对地震和滑坡链式灾害作用下桥梁结构易损性的研究较少。建立了地震和滑坡联合作用下桥梁结构性态分析框架并以某三跨连续梁为例,采用OpenSees软件建立了全桥非线性有限元模型,考虑了桩土相互作用的影响,并基于非线性时程分析研究了滑坡体积与滑坡运动距离等因素对桥梁结构易损性曲线的影响。结果表明:在地震和滑坡联合作用下桥梁结构累积损伤明显增大;在滑坡运动距离为150 m范围内,桥梁结构失效概率明显增大,当滑坡运动距离超过250 m时,桥梁结构失效概率增幅较小;当PGA为1g且滑坡运动距离为100 m时,体积为1×10^(7 )m^(3)量级的滑坡对桥梁结构破坏作用最大,导致桥梁结构完全失效的概率将增加60%以上;地震和滑坡的存在会显著增大桥梁结构在不同地震动水平下的失效概率,在选址时应予以充分考虑。