Refinement of the Proposed Gamma-Ray Burst Time Delay Model

This paper is the second instalment in our study of the observed time delay in the arrival times of radio photons emanating from Gamma Ray Bursts (GRBs). The mundane assumption in contemporary physics as to the cause of these pondersome time delays is that they are a result of the photon being endowed with a non-zero mass. While we do not rule out the possibility of a non-zero mass for the photon, our working assumption is that the major cause of these time delays may very well be that these photons are travelling in a rarefied cosmic plasma in which the medium’s electrons interact with the electric component of the Photon, thus generating tiny currents that lead to dispersion, hence, a frequency-dependent speed of Light (FDSL). In the present instalment, we “improve” on the model presented in the first instalment by dropping the assumption that the resultant pairs of these radio photons leave the shock front simultaneously. The new assumption of a non-simultaneous— albeit systematic—emission of these photon pairs allows us to obtain a much more convincing and stronger correlation in the time delay. This new correlation allows us to build a unified model for the four GRBs in our sample using a relative distance correction mechanism. The new unified model allows us to obtain as our most significant result a value for the frequency equivalence of the interstellar medium (ISM)’s conductance ν* ~ 1.500 ± 0.009 Hzand also an independent distance measure to the GRBs where we obtain for our four GRB samples an average distance of: ~69.40 ± 0.10, 40.00 ± 0.00, 58.40 ± 0.40, and 86.00 ± 1.00 Mpc, for GRB 030329, 980425, 000418 and 021004 respectively.

Underestimated relationship between westerly wind bursts and ENSO in CMIP6 models

观测表明,热带太平洋的西风爆发(WWBs)在厄尔尼诺南方涛动(ENSO)的发生,发展和多样性中起着关键作用.因此,在耦合模式中真实地再现WWBs对于改进ENSO的模拟和预测有重要意义.在本研究中,作者发现CMIP6的耦合模式的集合平均能很好地再现了热带太平洋WWB发生频率的纬向分布及其年际变动.然而,大多数CMIP6模型极大低估了WWB和ENSO的线性关系.这可能是因为大多数CMIP6模式里海气耦合强度低于观测:海气耦合强度与WWB-ENSO关系的模式间相关系数高达0.91.

Experimental models of high-risk bowel anastomosis in rats:A systematic review

BACKGROUND Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity,that negatively affect the patients’quality of life.Experimental studies play an important role in understanding the pathophysiological background of anastomotic healing and there are still many fields that require further investigation.Knowledge drawn from these studies can lead to interventions or techniques that can reduce the risk of anastomotic leak in patients with high-risk features.Despite the advances in experimental protocols and techniques,designing a high-quality study is still challenging for the investigators as there is a plethora of different models used.AIM To review current state of the art for experimental protocols in high-risk anastomosis in rats.METHODS This systematic review was performed according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.To identify eligible studies,a comprehensive literature search was performed in the electronic databases PubMed(MEDLINE)and Scopus,covering the period from conception until 18 October 2023.RESULTS From our search strategy 102 studies were included and were categorized based on the mechanism used to create a high-risk anastomosis.Methods of assessing anastomotic healing were extracted and were individually appraised.CONCLUSION Anastomotic healing studies have evolved over the last decades,but the findings are yet to be translated into human studies.There is a need for high-quality,well-designed studies that will help to the better understanding of the pathophysiology of anastomotic healing and the effects of various interventions.

Assessment of rockburst hazard by quantifying the consequence with plastic strain work and released energy in numerical models

Quantifying the rockburst consequence is of critical importance to reduce the hazards with preventative measures in underground mines and deep tunnels. Contours of energy components within a pillar model are plotted at different rockmass damage stages, and plastic strain work and released energy are proposed as indicators of rockmass damage consequence. One pillar model under different loading stiffness is simulated to assess indicators of pillar burst and the resulting damages. The results show the rockmass damage under soft loading stiffness has larger magnitude of plastic strain work and released energy than that which is under stiff loading stiffness, indicating the rockburst consequence can be quantified with plastic strain work and released energy in numerical models. With the quantified rockburst consequence,preventative measures can be taken to avoid severe hazards to mine safety.

A dynamic ejection coal burst model for coalmine roadway collapse

In this study,we established a dynamic ejection coal burst model for a coalmine roadway subject to stress,and held that the stress concentration zone at the roadway side is the direct energy source of this ejection.The formation and development of such burst undergoes three stages:(1)instability and propagation of the cracks in the stress concentration zone,(2)emerging of a layered energy storage structure in the zone,and(3)ejection of coal mass or coal burst due to instability.Moreover,we figured out the initial strength of periodic cracks is parallel to the maximal dominant stress direction in the stress concentration zone and derived from the damage strain energy within the finite area of the zone based on the Griffith energy theory.In addition,we analyzed the formation process of the layered energy storage structure in the zone,simplified it as a simply supported restraint sheet,and calculated the minimum critical load and the internally accumulated elastic energy at the instable state.Furthermore,we established a criterion for occurrence of the coal burst based on the variational principle,and analyzed the coal mass ejection due to instability and coal burst induced by different intensity disturbances.At last,with the stratum conditions of Junde Coalmine as the model prototype,we numerically simulated the load displacement distribution of the stress concentration zone ahead of the working face disturbed by the main roof-fracture-induced dynamic load during the mining process as well as their varying characteristics,and qualitatively verified the above model.

BURST-LDA: A NEW TOPIC MODEL FOR DETECTING BURSTY TOPICS FROM STREAM TEXT

Topic models such as Latent Dirichlet Allocation(LDA) have been successfully applied to many text mining tasks for extracting topics embedded in corpora. However, existing topic models generally cannot discover bursty topics that experience a sudden increase during a period of time. In this paper, we propose a new topic model named Burst-LDA, which simultaneously discovers topics and reveals their burstiness through explicitly modeling each topic's burst states with a first order Markov chain and using the chain to generate the topic proportion of documents in a Logistic Normal fashion. A Gibbs sampling algorithm is developed for the posterior inference of the proposed model. Experimental results on a news data set show our model can efficiently discover bursty topics, outperforming the state-of-the-art method.

3-D modeling of rock burst in pillar No. 19 of Fetr6 chromite mine

Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 19 failed and other pillars failed progressively as a domino effect and 4000 m2 of mine collapsed within a few minutes, consequently. For detail investigation, two 3-D numerical models were developed by 3Dec. The first, a base model, was used for estimation of stress on pillars just before failure and the other for investigation of rock burst in pillar No. 19. The results show that discontinuity parameters such as friction angle and shear stiffness is critical parameters in this pillar failure. In addition, it indicates that W/H ratio equal 0.3, the lack of ore extraction strategy and inadequate roof support are the major reasons for this failure. In this paper, the procedure of study was described.

Modelling and Analysis of the Hubble Diagram of 280 Type SNIa Supernovae and Gamma Ray Bursts Redshifts with Analytical and Empirical Redshift/Magnitude Functions

Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding or static universe. At redshifts > 2 - 3 ΛCDM models show a poor agreement with the observed data. Based on the results presented in this paper, the Hubble diagram test does not necessarily support the idea of expansion according to the big-bang concordance model.

Entity Burst Discriminative Model for Cumulative Citation Recommendation

Knowledge base acceleration-cumulative citation recommendation(KBA-CCR)aims to detect citation-worthiness documents from a chronological stream corpus for a set of target entities in a knowledge base.Most previous works only consider a number of semantic features between documents and target entities in the knowledge base,and then use powerful machine learning approaches such as logistic regression to classify relevant documents and non-relevant documents.However,the burst activities of an entity have been proved to be a significant signal to predict potential citations.In this paper,an entity burst discriminative model(EBDM)is presented to substantially exploit such burst features.The EBDM presents a new temporal representation based on the burst features,which can capture both temporal and semantic correlations between entities and documents.Meanwhile,in contrast to the bag-of-words model,the EBDM can significantly decrease the number of non-zero entries of feature vectors.An extensive set of experiments were conducted on the TREC-KBA-2012 dataset.The results show that the EBDM outperforms the performance of the state-of-the-art models.

Development of a displacement-reactivity feedback model for dynamic behavior simulation in fast burst reactor

In this study, a displacement-reactivity feedback model, which can directly represent the inherent ‘‘thermal expansion extinction effect'' of fast burst reactors(FBRs),was developed with the aid of the static neutron transport component of the FBR-MPC code. Dynamic behaviors of bursts in the Godiva I reactor were simulated by coupling the simplified multiphysics models consisting of the point kinetic equations for neutronics, adiabatic equation for temperature, and thermoelastic equations for displacement/stress with the developed model. The results were compared with the corresponding experimental data and those obtained using the traditional fission yield(temperature rise)-reactivity feedback models. It was found that the developed model can provide good results for the bursts with no or a small inertia effect. For the bursts with a prominent inertia effect, the smaller burst width and asymmetric distribution of the fission rate curve, noticed in the experiments but not evident using the traditional models, can be reproduced. In addition, the realistic oscillations in reactivity and fission rate caused by the core vibration, as well as the deeper sub-prompt criticality in the plateau following the burst, can be observed. Therefore, the developed displacement-reactivity feedback model can be expected to be an effective tool for calculating the dynamic behaviors of bursts.

The Phenomenon of Neural Bursting and Spiking in Neurons: Morris-Lecar Model

In this study, we explore the interesting phenomenon of firing spikes and complex dynamics of Morris-Lecar model. We consider a set of parameters such that the model exhibits a wide range of phenomenons. We investigate the influences of injected current and temperature on the spiking dynamics of Morris-Lecar model. Moreover, we study bifurcations, and computational properties of this neuron model. Also, we define a bound (Max and Min voltage) for membrane potential and a certain voltage value or threshold for firing the spikes. Studying the two co-dimension bifurcations demonstrates much more complicated behaviors for this single neuron model. We also describe the phenomenon of neural bursting, and investigate the dynamics of Morris-Lecar model as a square-wave burster, elliptic burster and parabolic burster.

A CUSPC ATASTROPHIC MODEL AND TIME EFFECT OF ROCK BURSTS OF A

Ａｍｅｃｈａｎｉｃａｌｍｏｄｅｌｆｏｒｔｈｅｒｏｃｋｂｕｒｓｔｓｏｆａｎｉｓｏｌａｔｅｄｃｏａｌｐｉｌｌａｒｗａｓｄｅｖｅｌｏｐｅｄａｎｄｔｈｅｍｅｃｈａｎｉｓｍｏｆｔｈｅｉｎｓｔａｂｉｌ－ｉｔｙｏｆｔｈｅｒｏｃｋｂｕｒｓｔｓｗａｓｓｔｕｄｉｅｄｂｙａｐｐｌｙｉｎｇｃｕｓｐｃａｔａｓｔｒｏｐｈｉｃｔｈｅｏｒｙ．Ｉｔｗａｓｅｘｐｏｕｎｄｅｄｔｈａｔｔｈｅｏｃｃｕｒｒｅｎｃｅｓｃｏｎｄｉ－ｔｉｏｎｓｏｆｒｏｃｋｂｕｒｓｔｓｃａｎｂｅａｔｔｒｉｂｕｔｅｄｔｏｔｈｅｃｏｎｄｉｔｉｏｎｔｈａｔｔｈｅｓｙｓｔｅｍａｃｃｅｐｔｓｅｎｏｕｇｈｅｎｅｒｇｙｆｒｏｍｅｘｔｅｒｎａｌｅｎｖｉｒｏｎ－ｍｅｎｔａｎｄｔｈｅｃｏｎｄｉｔｉｏｎｔｈａｔｔｈｅｅｎｅｒｇｙａｃｃｕｍｕｌａｔｅｄｉｎｓｙｓｔｅｍｉｓｒｅｌｅａｓｅｄｓｕｄｄｅｎｌｙ．Ｉｔｉｓｔｈｅｃａｕｓｅｏｆｔｈｅｒｏｃｋｂｕｒｓｔｓｈｙｓｔｅｒｅｓｉｓｔｈａｔｃｏｎｔｒｏｌｖａｒｉａｂｌｅｓｄｏｎ’ｔｓａｔｉｓｆｙｔｈｅｅｑｕａｔｉｏｎｏｆｂｉｆｕｒｃａｔｉｏｎｓｅｔｕｎｌｅｓｓａｐｉｅｃｅｏｆｐｅｒｉｏｄｈａｓｅｌａｐｓｅｄ．Ｆｉｎａｌ－ｌｙ，ｔｈｅｉｎｆｌｕｅｎｃｅｏ?

基于液压胀破测试方法的聚合物防水膜多轴拉伸性能表征

本研究设计了一种基于液压胀破的多轴拉伸测试装置和数据处理方法,以准确表征聚合物防水膜的拉伸性能。测试结果显示:随着防水膜厚度的增加,拉伸峰值应力降低;随着试件直径的增加,拉伸峰值应力增加;与单轴拉伸相比,多轴拉伸避免了“颈缩”效应,断裂伸长率降低;防水膜的应力-应变曲线符合线性应变强化弹塑性模型,并可通过多轴拉伸试验拟合得到相关参数。结论表明,多轴拉伸方法结果更接近实际工况下的应力-应变响应,可为合理评估防水膜在工程环境中的力学性能提供参考和借鉴。

用于大尺度模型发动机高频PLIF测量的脉冲串紫外激光系统

针对大尺度模型发动机试验台工作时间短(~百毫秒到秒量级)和激光能量要求高(>1 mJ)的特点,常规的紫外激光系统不能满足发动机燃烧流场精细化测量需求,要求用于高频平面激光诱导荧光(PLIF)测量的紫外激光系统同时满足脉冲串时间间隔短和激光输出能量高,并且系统具有高可靠性和环境适应性。设计了一套用于真实发动机地面试验台高频PLIF测量的脉冲串紫外激光系统,能够获取有效的火焰动力学数据。脉冲串紫外激光系统采用自主研制的脉冲串模式激光器泵浦染料激光器,具备能量监测、波长监测和片光分布监测等功能,可以校正激光参数对测量结果的影响。其中脉冲串模式激光器采用电光调Q、脉冲串模式和MOPA技术,使输出的泵浦激光具有高脉冲能量(~50 mJ@532 nm)、短脉冲宽度(~10.8 ns)和较高的脉冲串频率(20 Hz)。脉冲串紫外激光系统的串时间间隔为50 ms,是国外激光器脉冲串间隔时间的1/200;系统整体转换效率为6%,紫外单脉冲能量为2.95 mJ@283 nm,是国外连续脉冲激光器典型能量值的7倍。为满足发动机地面试验台测量需求,自主集成了工程可用的高可靠性移动式10 kHz PLIF测量系统,具有抗震、防潮和防尘等功能,提升了高频PLIF系统的环境适应能力。国内首次在中国空气动力研究与发展中心的脉冲燃烧风洞上实现了大尺度模型发动机燃烧流场远距离大视场成像测量(~15 cm),获得了高信噪比的氢燃料及乙烯燃料高动态燃烧过程可视化结果。未来可结合光谱图像特征提取与分析方法对其燃烧状态和动态过程开展研究,为发动机复杂流动燃烧机理研究、CFD仿真和发动机设计水平提升提供支撑。

考虑张力制度影响的碳纤维缠绕容器爆破性能预测与仿真插件开发

针对缠绕张力对碳纤维缠绕容器承载性能影响规律尚不明确的问题,基于ABAQUSTM软件开发了一套用户友好、自主选择性好且高效的插件工具,能够自动化完成模型建立和相关设置工作,实现了考虑多种缠绕工艺参数的容器结构精细化建模。基于该插件工具,对碳纤维缠绕容器在不同缠绕张力制度下的爆破性能进行了参数化分析,通过爆破试验验证了数值模型的有效性。对于直径为Ф155 mm和Ф474 mm的容器,90 N-80 N-60 N和200 N-180 N-160 N逐层减小的缠绕张力制度将提高容器的爆破性能;对于20 N和30 N递减张力制度,直径Ф474 mm容器的爆破压强随着内层张力的减小逐渐降低,当张力递减幅度增加时,容器的爆破压强趋于稳定,其下降幅度由16.79%减小到3.05%。此外,容器封头段与筒身段过渡区域的应变水平最高,为碳纤维缠绕容器的薄弱位置。

Ghostburster模型鞍结分岔点附近放电模式的转迁控制

在不同的电流刺激下,ghostburster模型表现出周期放电、混沌簇放电、周期簇放电等多种放电模式.其中,周期放电和混沌簇放电之间的转迁是通过极限环的鞍结分岔实现的.应用washout滤波器实现了ghostburster模型鞍结分岔点周围放电模式的转迁;并通过快慢系统分解方法分析了放电模式转迁的内在机制.研究发现快子系统固定点的鞍结分岔和快子系统从周期一极限环转换到周期二极限环的临界点在树突产生不完全放电过程中起到关键作用.Washout滤波器的加入改变了树突膜电位极大值的分岔点的位置,从而改变了ghostburster模型的放电模式.

基于顶板结构特征的冲击危险性评价方法及应用

目前煤矿普遍采用的冲击危险性评价方法忽视了岩层层位、厚度等对冲击危险性评价结果的影响,致使现有冲击危险性评价体系对不同地层结构下顶板冲击危险性评价准确度不足。根据采空区覆岩破坏程度,建立了全悬顶结构、半悬顶结构及完全移动结构3类顶板结构力学模型,分析了各类顶板结构类型下的应力传递机制,提出了基于3类顶板结构与实测矿震数据相结合的动静载叠加应力计算方法及考虑顶板结构特征的冲击危险性评价指标及评价方法,并分析了岩层强度系数、关键层厚度以及岩层下沿距工作面距离对冲击特征参数p的影响规律;依托鄂尔多斯市某矿2201工作面、济宁市某矿63上06工作面及菏泽市某矿3301工作面地层结构条件,进行了顶板岩层结构下动静载叠加应力及冲击危险性评价参数的计算,并根据计算结果进行了冲击危险性评价验证分析。

某空炸杀伤弹对地面人员目标毁伤效能研究

为充分评价某空炸杀伤弹战斗部的毁伤能力,利用靶场静爆、动爆试验和数值模拟方法开展了空炸杀伤弹杀伤威力研究,分析了战斗部破片飞散规律,确定了破片落点分布规律,依据人体易损性分析A-S准则,获得了空炸弹在落角、落速、炸高不同运动参数下有效杀伤面积。结果表明:试验和数值模拟的破片飞散规律和落点分布规律一致。以地面人员为杀伤目标,通过数值模拟计算了空炸姿态对空炸弹有效杀伤面积受炸高影响的规律。空炸弹有效杀伤面积受炸高的影响较大,受落角和落速的影响较小,通过落速、落角和炸高的最佳匹配,使破片有效杀伤面积最大,可为该型空炸杀伤弹毁伤实际应用提供参考。

MIKE软件技术在水库溃坝洪水数值模拟中的应用研究

当前,水库大坝受到超频率的洪水以及强震破坏,而容易导致溃决风险。针对水库大坝溃决相关问题,融合BREACH和MIKE21构建耦合模型,并用于溃坝洪水数值模拟试验。结果表明,7种方案最大下泄流量为方案1的18.39×10^(4) m^(3)/s;方案1洪峰向地点C汇入点的洪水最大流量比邢台坝址下降约44%。方案1的溃坝洪水水位始终最高,A地最高为306m。综合来看,耦合模型在水库溃坝洪水数值模拟中具备有效性,在实际的水库防洪避险中具备实用性。

A STUDY ON THE SCALING RATE MODEL OF CALCIUM CARBONATE IN SATURATED WATER SYSTEM

1 INTRODUCTIONCalcium carbonate scaling is quite common in chemical processes,especially in heatexchangers.Only limited work has been done in mathematical modelling describingthe calcium carbonate scaling phenomenon.Hasson’s ionic diffusion model happenedto be one being rather broadly accepted.