Innovative backfilling longwall panel layout for better subsidence control effect-separating adjacent subcritical panels with pillars

In recent years,field trials of non-pillar longwall mining using complete backfill have been implemented successively in the Chinese coal mining industry.The objective of this paper is to get a scientific understanding of surface subsidence control effect using such techniques.It begins with a brief overview on complete backfill methods primarily used in China,followed by an analysis of collected subsidence factors under mining with complete backfill.It is concluded that non-pillar longwall panel layout cannot protect surface structures against damages at a relatively large mining height,even though complete backfill is conducted.In such cases,separated longwall panel layout should be applied,i.e.,panel width should be subcritical and stable coal pillars should be left between the adjacent panels.The proposed method takes the principles of subcritical extraction and partial extraction;in conjunction with gob backfilling,surface subsidence can be effectively mitigated,thus protecting surface buildings against mining-induced damage.A general design principle and method of separated panel layout have also been proposed.

基于Command and Control通信信道流量属性聚类的僵尸网络检测方法

僵尸网络(Botnet)是一种从传统恶意代码形态进化而来的新型攻击方式,为攻击者提供了隐匿、灵活且高效的一对多命令与控制信道(Command and Control channel,C&C)机制,可以控制大量僵尸主机实现信息窃取、分布式拒绝服务攻击和垃圾邮件发送等攻击目的。该文提出一种与僵尸网络结构和C&C协议无关,不需要分析数据包的特征负载的僵尸网络检测方法。该方法首先使用预过滤规则对捕获的流量进行过滤,去掉与僵尸网络无关的流量;其次对过滤后的流量属性进行统计;接着使用基于X-means聚类的两步聚类算法对C&C信道的流量属性进行分析与聚类,从而达到对僵尸网络检测的目的。实验证明,该方法高效准确地把僵尸网络流量与其他正常网络流量区分,达到从实际网络中检测僵尸网络的要求,并且具有较低的误判率。

基于Model/View/Controller的电子商务研究

分析了传统电子商务系统的缺陷 ,电子商务发展趋势 ,分析了M/V/C(Model/View/Controller)技术 ,提出了基于M/V/C电子商务并且分析了其体系结构及框架结构 ,以及在此框架之上构建电子商务的方法。

Threshold decision for instrument control system and its application in nuclear power plant

Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.

VC++中Custom Control的设计与实现

目前很多软件开发工具支持Custom Control类型的控件,这种控件可以使设计者从包括最基础的窗口类在内的各个方面,对控件的显示和行为进行全方位的控制,具有极大的灵活性和扩充性,在不少需要复杂或者特色界面显示的场合,发挥重要作用。本文介绍Custom Control的设计方法,作为实例同时介绍RICHEDIT20A的使用。

3D-DSA与Dyna-CT在颅内支架置入术中的临床应用研究

目的探讨三维DSA血管成像(3D-DSA)及数字平板造影机的C臂旋转并断层重建技术(DynaCT)在颅内支架置入术患者中的临床应用。方法选择2019年1月-2020年6月厦门大学附属中山医院收治92例颅内动脉狭窄患者,所有患者均行颅内支架置入术治疗,分为对照组(n=38例)和观察组(n=54例)。对照组采用3D-DSA引导,观察组采用DynaCT引导,术后进行12个月门诊随访,比较两组改良Rankin量表(mRS)评分、手术成功率、并发症、支架再狭窄及斑块检出率。结果观察组术后4个月、8个月及12个月mRS评分、支架成形术耗时低于对照组(P<0.05);观察组Dyna-CT的术前规划、观察到支架表面图像与术中所见吻合,手术成功率为83.33%,高于对照组63.16%(P<0.05);两组围术期并发症发生率无统计意义(P>0.05);观察组手术后进行12个月门诊随访,患者支架再狭窄、血管狭窄部位斑块检出率低于对照组(P<0.05)。结论DynaCT用于颅内支架置入术中能改善患者症状,缩短支架成形术耗时,有助于提高手术成功率,未增加并发症发生率,能降低血管狭窄部位斑块检出率,值得推广应用。

船用C型夹层板隔声性能研究

夹层板作为一种新型结构,具有设计性强、重量轻、比刚度高、减振隔声性能好等优点,已被应用于各种工程结构。然而,其夹层结构形式种类繁多,对复杂夹层结构的隔声性能进行理论分析比较困难,亟需开展新的近似分析方法。本文针对船用C型夹层板,基于弹簧、扭簧与集中质量的等效方法,建立C型夹层板的声振耦合控制方程,利用空间谐波展开法,推导C型夹层结构的传声损失表达式,讨论夹层板系统参数对结构隔声性能的影响规律。结果表明,材料属性与夹层板结构面板的厚度对C型夹层板结构隔声性能的影响较大。同时,通过有限元仿真,验证了理论分析的有效性。

基于PLC的加工中心操作面板控制功能的设计

针对配置KND 2000Mci数控系统的CB-SKZT600加工中心,设计了该数控机床工作模式的选择、伺服轴进给倍率、伺服轴快速倍率、主轴速度倍率等功能,包括各功能硬件控制电路的设计,以及编制相应的PLC控制梯形图,以期为其他加工中心操作面板控制功能设计提供一种简捷实用的解决思路。

Risk factors for liver-related mortality in chronic hepatitis C patients:A deceased case-living control study

AIM: To investigate the risk factors for liver-related mortality in chronic hepatitis C (CHC) patients.

Quality control measures for lowering the seroconversion rate of hemodialysis patients with hepatitis B or C virus

BACKGROUND: Hemodialysis (HD) patients are at high risk of infection by hepatitis B virus (HBV) or hepatitis C virus (HCV). The present study was designed to determine the impact of quality control measures on the prevention of transmission of blood-borne viruses. METHODS: A total of 6182 adult maintenance HD patients from all HD units in Zhejiang Province were recruited on January 1, 2007. The baseline demographic and clinical characteristics were recorded and all patients were followed up until death or survival at 4 years later. The Quality Control Standards of Hemodialysis were gradually implemented in HD units. The HBV or HCV seroconversion rates of the recruited patients were calculated and compared every year during the observation period. RESULTS: The prevalence of HBV was 8.3% at the beginning of the study, and 6.6% for HCV. With the implementation of the HD quality control measures, the HBV seroconversion rate tended to decrease year by year (χ 2 =6.620, P=0.085), and the HCV seroconversion rate decreased significantly (χ 2 =10.41, P=0.015). Compared with the data in 2007, the HBV seroconversion rate (χ 2 =4.204, P=0.040, relative risk ratio 0.393, 95% CI 0.156-0.991) and the HCV seroconversion rate (χ 2 =7.373, P=0.007, relative risk ratio 0.386, 95% CI 0.189-0.787) decreased significantly in 2010. CONCLUSION: Quality control measures for HD decreased the seroconversion rates of HBV or HCV in HD patients, showing that updated quality control measures reduce the risk for transmission of blood-borne viruses in the HD population.

Indicators of glycemic control in patients with gestational diabetes mellitus and pregnant women with diabetes mellitus

Recently, it has become clear that mild abnormal glucose tolerance increases the incidence of perinatal maternalinfant complications, and so the definition and diagnostic criteria of gestational diabetes mellitus(GDM) have been changed. Therefore, in patients with GDM and pregnant women with diabetes mellitus, even stricter glycemic control than before is required to reduce the incidence of perinatal maternal-infant complications. Strict glycemic control cannot be attained without an indicator of glycemic control; this review proposes a reliable indicator. The gold standard indicator of glycemic control in patients with diabetes mellitus is hemoglobin A1c(Hb A1c); however, we have demonstrated that Hb A1 c does not reflect glycemic control accurately during pregnancy because of iron deficiency. It has also become clear that glycated albumin, another indicator of glycemic control, is not influenced by iron deficiency and therefore might be a better indicator of glycemic control in patients with GDM and pregnant women with diabetes mellitus. However, largepopulation epidemiological studies are necessary in order to confirm our proposal. Here, we outline the most recent findings about the indicators of glycemic control during pregnancy including fructosamine and 1,5-anhydroglucitol.

Principal Face-based Recognition Approach for Machining Features of Aircraft Integral Panels

Feature recognition aims at extracting manufacturing features with geometrical information from solid model and is considered to be an efficient way of changing the interactive NC machining programming mode.Existing recognition methods have some disadvantages in practical applications.They can essentially handle prismatic components with regular shapes and are difficult to recognize the intersecting features and curved surfaces.Besides,the robustness of them is not strong enough.A new feature recognition approach is proposed based on the analysis of aircraft integral panels＇ geometry and machining characteristics.In this approach,the aircraft integral panel is divided into a number of local machining domains.The machining domains are extracted and recognized first by finding the principal face of machining domain and extracting the sides around the principal face.Then the machining domains are divided into various features in terms of the face type.The main sections of the proposed method are presented including the definition,classification and structure of machining domain,the relationship between machining domain and principal face loop,the rules of machining domains recognition,and the algorithm of machining feature recognition.In addition,a robotic feature recognition module is developed for aircraft integral panels and tested with several panels.Test results show that the strategy presented is robust and valid.Features extracted can be post processed and linked to various downstream applications.The approach is able to solve the difficulties in recognizing the aircraft integral panel＇s features and automatic obtaining the machining zone in NC programming,and can be used to further develop the automatic programming of NC machining.

Application of Super-Synchronization Speed Control Technology in Two 80 MVA Motor-Generator Units of HL-2A

Two sets of super-synchronization speed control assemblies for two 80 MVA motor-generator units have been developed successfully in order to satisfy the demand of the toroidal field system in the HL-2A tokamak. Based on the three-phase logical no-circumfluence a.c./a.c. cycloconverter, the speeds of two 2500 kW double fed drive motors have been regulated by means of the vector control technology. The maximum operating speed of each motor- generator unit has been raised from 1488 rpm （revolutions per minute） to 1650 rpm and the released energy of each unit during a pulsed discharge can reach 500 MJ. As a result, the toroidal field system has the capacity to provide 2.8 tesla （T） in HL-2A experiments.

Utility of different glycemic control metrics for optimizing management of diabetes

The benchmark for assessing quality of long-term glycemic control and adjustment of therapy is currently glycated hemoglobin(Hb A1c). Despite its importance as an indicator for the development of diabeticcomplications, recent studies have revealed that this metric has some limitations; it conveys a rather complex message, which has to be taken into consideration for diabetes screening and treatment. On the basis of recent clinical trials, the relationship between Hb A1 c and cardiovascular outcomes in long-standing diabetes has been called into question. It becomes obvious that other surrogate and biomarkers are needed to better predict cardiovascular diabetes complications and assess efficiency of therapy. Glycated albumin, fructosamin, and 1,5-anhydroglucitol have received growing interest as alternative markers of glycemic control. In addition to measures of hyperglycemia, advanced glucose monitoring methods became available. An indispensible adjunct to Hb A1 c in routine diabetes care is selfmonitoring of blood glucose. This monitoring method is now widely used, as it provides immediate feedback to patients on short-term changes, involving fasting, preprandial, and postprandial glucose levels. Beyond the traditional metrics, glycemic variability has been identified as a predictor of hypoglycemia, and it might also be implicated in the pathogenesis of vascular diabetes complications. Assessment of glycemic variability is thus important, but exact quantification requires frequently sampled glucose measurements. In order to optimize diabetes treatment, there is a need for both key metrics of glycemic control on a day-to-day basis and for more advanced, user-friendly monitoring methods. In addition to traditional discontinuous glucose testing, continuous glucose sensing has become a useful tool to reveal insufficient glycemic management. This new technology is particularly effective in patients with complicated diabetes and provides the opportunity to characterize glucose dynamics. Several continuous glucose monitoring(CGM) systems, which have shown usefulness in clinical practice, are presently on the market. They can broadly be divided into systems providing retrospective or real-time information on glucose patterns. The widespread clinical application of CGM is still hampered by the lack of generallyaccepted measures for assessment of glucose profiles and standardized reporting of glucose data. In this article, we will discuss advantages and limitations of various metrics for glycemic control as well as possibilities for evaluation of glucose data with the special focus on glycemic variability and application of CGM to improve individual diabetes management.

Glycemic control indicators in patients with neonatal diabetes mellitus

Neonatal diabetes mellitus(NDM) is a type of diabetes mellitus caused by genetic abnormality which devel ops in insulin dependent state within 6 mo after birth HbA1c is widely used in clinical practice for diabetes mellitus as the gold standard glycemic control indica tor; however, fetal hemoglobin(HbF) is the main he moglobin in neonates and so HbA1c cannot be used as a glycemic control indicator in NDM. Glycated albumin(GA), another glycemic control indicator, is not affected by HbF. We reported that GA can be used as a glycemic control indicator in NDM. However, it was later found that because of increased metabolism of albumin, GA shows an apparently lower level in relation to plasma glucose in NDM; measures to solve this problem were needed. In this review, we outlined the most recen findings concerning glycemic control indicators in neo nates or NDM.

Reverse time-dependent effect of alphafetoprotein and disease control on survival of patients with Barcelona Clinic Liver Cancer stage C hepatocellular carcinoma

AIM To characterize the survival of cirrhotic patients with Barcelona Clinic Liver Cancer(BCLC) stage C hepatocellular carcinoma(HCC) and to ascertain the factors predicting the achievement of disease control(DC).METHODS The cirrhotic patients with BCLC stage C HCC evaluated by the Hepatocatt multidisciplinary group were subjected to the investigation. Demographic, clinical and tumor features, along with the best tumor response and overall survival were recorded. RESULTS One hundred and ten BCLC stage C patients were included in the analysis; the median overall survival was 13.4 mo(95%CI: 10.6-17.0). Only alphafetoprotein(AFP) serum level > 200 ng/m L and DC could independently predict survival but in a time dependent manner, the former was significantly associated with increased risk of mortality within the first 6 mo of follow-up(HR = 5.073, 95%CI: 2.159-11.916, P = 0.0002), whereas the latter showed a protective effect against death after one year(HR = 0.110, 95%CI: 0.038-0.314, P < 0.0001). Only patients showing microvascular invasion and/or extrahepatic spread recorded lower chances of achieving DC(OR = 0.263, 95%CI: 0.111-0.622, P = 0.002).CONCLUSION The BCLC stage C HCC includes a wide heterogeneous group of cirrhotic patients suitable for potentially curative treatments. The reverse and time dependent effect of AFP serum level and DC on patients' survival confers them as useful predictive tools for treatment management and clinical decisions.

Beyond 5G Networks: Integration of Communication, Computing, Caching, and Control

In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular networks.Such challenges can be potentially overcome by integrating communication,computing,caching,and control(i4C)technologies.In this survey,we first give a snapshot of different aspects of the i4C,comprising background,motivation,leading technological enablers,potential applications,and use cases.Next,we describe different models of communication,computing,caching,and control(4C)to lay the foundation of the integration approach.We review current stateof-the-art research efforts related to the i4C,focusing on recent trends of both conventional and artificial intelligence(AI)-based integration approaches.We also highlight the need for intelligence in resources integration.Then,we discuss the integration of sensing and communication(ISAC)and classify the integration approaches into various classes.Finally,we propose open challenges and present future research directions for beyond 5G networks,such as 6G.

Control of reactive dividing wall column for selective hydrogenation and separation of C3 stream

In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.

An operational approach to ground control in deep mines

As mines go deeper and get larger,mine designs become more fragile largely due to the response of the rock mass to mining.Ground control and rock support become important levers in the mine construction schedule,production performance,and excavation health.For example,in cave mines,the production footprint together with associated mine infrastructure are significant investments in a modern caving operation.This investment must be protected and maintained to reduce the risk of ground-related production disruptions.It is necessary to preserve the health of these excavations and their maintenance through an effective rock support design.Rock support thus becomes a strategic element in asset management.This article focuses on support design for brittle ground when displacements induced by stress-fracturing consume much of the support’s capacity.It deals with the functionality of the support in deforming ground.Several interlinked concepts are important when assessing excavation health.Designs must not only account for load equilibrium but also for deformation compatibility and capacity consumption.Most importantly,the support’s displacement capacity is being consumed when the rock mass is deformed after support installation.Hence,it is necessary to design for the support capacity remaining at the time when the support is needed.If support capacity can be consumed,it can also be restored by means of preventive support maintenance(PSM).This concept for cost-effective ground control is introduced and illustrated on operational evidence.Furthermore,how design can impact construction costs and schedule are discussed.Support is installed to provide a safe environment and preserve an operationally functional excavation.It also must assure senior management that investments in high quality support and its maintenance will substantially reduce delays and with it,costs.It is demonstrated that the use of‘gabion-like’support systems can achieve these goals.A technical summary of the‘gabion panel’support system design is presented.

Proposal of Functional Thermal Control Systems for High-Power Micro-Satellite and Its Demonstration under Thermal Vacuum Condition

In previous years, several high-power micro-satellites below ~100 kg have been developed for high-functional spacecraft. This paper proposes a functional and high-power thermal control system with no power supply and a simple configuration for micro-satellite: 100 W, 3 U. The proposed system consists of a heat storage panel (HSP) with pitch type CFRP (Carbon Fiber Reinforced Polymer), a micro loop heat pipe (m-LHP) and a flexible re-deployable radiator (FRDR) as an active thermal control system. The aim of this research is to try not only to verify the thermal control devices, but also to perform a water phase change experiment as a payload using an electric power generation of 100 W in space environment. In this paper, the basic design of the satellite, the analysis of the feasibility by the thermal mathematical model, and the fabrication of thermal test model including water phase chamber are reported. The main results of thermal analysis as feasibility verification showed that the paddles could absorb the thermal energy up to 97 W at the solar input of 180 W, and the operating temperature of bus equipment became within the allowable temperature range (0&deg;C - 40&deg;C). At thermal vacuum test, the difference between the analysis and the experiment for the temperature history of water due to the discordance for the value of thermal conductance was discussed.