Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Crystal Facet Engineering of TiO_(2) Nanostructures for Enhancing Photoelectrochemical Water Splitting with BiVO_(4) Nanodots

Although bismuth vanadate(BiVO4)has been promising as photoanode material for photoelectrochemical water splitting,its charge recombination issue by short charge diffusion length has led to various studies about heterostructure photoanodes.As a hole blocking layer of BiVO4,titanium dioxide(TiO_(2)) has been considered unsuitable because of its relatively positive valence band edge and low electrical conductivity.Herein,a crystal facet engineering of TiO_(2) nanostructures is proposed to control band structures for the hole blocking layer of BiVO4 nanodots.We design two types of TiO_(2) nanostructures,which are nanorods(NRs)and nanoflowers(NFs)with different(001)and(110)crystal facets,respectively,and fabricate BiVO4/TiO_(2) heterostructure photoanodes.The BiVO4/TiO_(2) NFs showed 4.8 times higher photocurrent density than the BiVO4/TiO_(2) NRs.Transient decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination,which is originated from the formation of type II band alignment between BiVO4 nanodots and TiO_(2) NFs.This work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes.

Schemes for Splitting Quantum Information with Four-Particle Genuine Entangled States

我们为由把四粒子的真纠缠的状态用作量隧道切开 single-qubit 和 two-qubit 状态建议二个计划。在发送者执行钟基础以后(或三深裂的 GHZ- 基础) 她的粒子上的大小，和合作者在他们的粒子上操作单个粒子的大小，州的接收装置能重建由使用适当单一的操作的发送者的原来的状态。在为切开 two-qubit 状态的计划，特别地，接收装置需要介绍一个辅助粒子并且执行一 C 不操作。

The Coupling of Voltage and Frequecncy Response in Splitting Island and Its Effects on Load-shedding Relays

The voltage and frequency dynamics interact with each other in the island after splitting. The current frequency response model without considering the voltage effect would bring remarkable errors when analyzing the frequency dynamic progress in the island with large-capacity active-power shortage. In this paper, coupling effects of voltage and frequency are studied to indicate that initial reactive-power deficit and load characteristics have strong effects on the coupling effects of the voltage and frequency. Moreover, control effects of currently used under frequency load-shedding relays (UFLS) and under voltage load-shedding relays (UVLS) which are installed and executed independently are examined to find that it would sometimes cause excessive or inadequate control without considering the coupling, suggesting that it is necessary to develop coordinate control methods for voltage and frequency problems.

Dynamic analysis and split range control for maximization of operating range of continuous microbial fuel cell

Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter.In this paper,first principle-based model of variable volume microbial fuel cell is simulated.Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses.Classical PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo problem.Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set point.These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells.The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel cell.Also,there is no increase in the working volume of the constant volume microbial fuel cell.Hence,operating range of the microbial fuel cell is enhanced using split range controller.

An Identifier-Based Network Access Control Mechanism Based on Locator/Identifier Split

Legacy IP address-based access control has met many challenges, because the network nodes cannot be identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to build a network access control mechanism based on the permanent identifier. With the support of “Locator/Identifier Split” routing and addressing concept, the Identifier-based Access Control (IBAC) makes net-work access control more accurate and efficient, and fits for mobile nodes’ access control quite well. Moreover, Self-verifying Identifier makes it possible for the receiver to verify the packet sender’s identity without the third part authentication, which greatly reduces the probability of “Identifier Spoofing”.

Conditional Lot Splitting to Avoid Setups While Reducing Flow Time

Previous research has clearly and consistently shown that flow time advantages accrue from splitting production lots into smaller transfer batches or sub-lots. Less extensively discussed, and certainly undesired, is the fact that lot splitting may dramatically increase the number of setups required, making it impractical in some settings. This paper describes and demonstrates a primary cause of these “extra” setups. It then proposes and evaluates decision rules which selectively invoke lot splitting in an attempt to avoid extra setups. For the closed job shop environment tested, our results indicate that conditional logic can achieve a substantial portion of lot splitting’s flow time improvement while avoiding the vast majority of the additional setups which would be caused by previously tested lot splitting schemes.

Model-Based Split-Range Algorithm for the Temperature Control of a Batch Reactor

In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial losses, or in the pharmaceutical industry, it can result in an unusable batch. In these industries, batch reactors are commonly used, the control of which is essentially a problem of temperature control. In the industry, an increasing number of heating-cooling systems utilising three different temperature levels can be found, which are advantageous from an economic point of view. However, it makes the control more complicated. This paper presents a split-range designing technique using the model of the controlled system with the aim to design a split-range algorithm more specific to the actual sys- tem. The algorithm described provides high control performance when using it with classical PID-based cascade temperature control of jacketed batch reactors;however, it can be used with or as part of other types of controllers, for ex- ample, model-based temperature controllers. The algorithm can be used in the case of systems where only two as well as where three temperature levels are used for temperature control. Besides the switching between the modes of opera- tion and calculating the value of the manipulated variable, one of the most important functions of the split-range algo- rithm is to keep the sign of the gain of the controlled system unchanged. However, with a more system-specific split-range solution, not only can the sign of the gain be kept unchanged, but the gain can also be constant or less de- pendent on the state of the system. Using this solution, the design of the PID controller becomes simpler and can be implemented in existing systems without serious changes.

分体式自清洗工业废气余热回收装置设计

为解决化纤生产废气余热回收装置运行一段时间后因污垢层积而换热效率下降的问题,提出一种分体式自清洗工业废气余热回收装置。设计了分体式换热器,采用PLC控制刷洗机构、拉板小车和高压喷头,实现了换热翅片管排的自动分合和清洗功能。测试结果显示,分体式自清洗工业废气余热回收装置能维持较高的换热效率,较原有整体式装置效率提升大约5%,清洗时间由10h缩短为2.5h。该余热回收装置可提高能源利用效率,降低生产成本,减少维护时间,为低品位热能回收利用提供了参考。

一种新型分体式换流变压器有载分接开关

近年来发生了数起换流变压器有载分接开关在档位调节过程中爆炸起火的严重事故。针对此问题,提出了一种新型分体式换流变有载分接开关的设计方案,将切换开关部分与变压器本体分离,有效避免分接开关故障影响的扩大。切换开关各触头由真空永磁开关替代且操作机构独立配置,结合内部支路配置的电流采样装置,实现切换过程的监测可控。提出了分体式同步控制逻辑和切换开关分步控制逻辑,实现了分接开关调档过程的状态监测及故障保护。样机的试验结果验证了分体式换流变压器有载分接开关方案的可行性和有效性。

多断面多通道互联电网广域失步解列控制系统设计及实施

总结分析了多断面多通道区域互联电网失步振荡时可能存在的多断面失步存在选择性、同一断面不同通道失步不同时以及同一断面上部分通道失步特性不明显等特性,针对现有就地失步解列方案不适应上述特性的问题,采用基于就地装置动作允许命令,利用远方通信构建的广域失步解列系统方法,根据考虑解决现有就地失步解列方案问题、与现有就地失步解列功能的配合、系统防误设计以及异常情况下控制策略处理逻辑等主要设计原则,设计并实施了南方电网广域失步解列控制系统。RTDS仿真试验结果表明,该系统能够正确响应,有选择、快速、可靠地采取既定措施同时解列相关断面,有效解决现有就地失步解列方案的局限性,满足实际系统运行需要。

Split源光伏并网逆变器控制策略研究

用于存储可再生能源的并网电源转换系统需满足低成本,高效率和复杂度等要求。使用传统的并网逆变器时,通常需要在前级加入一个升压变换电路,从而造成了两级结构。单级并网逆变器只用一级能量变换就可实现DC-AC并网逆变功能,因此在体积、成本、质量和复杂度等方面均优于两级结构。基于上述分析,研究了Split源逆变器(SSI),作为阻抗网络型逆变器的替代选择。分析了SSI的工作原理,建立了平均状态模型。在此基础上,使用了一种改进的调制策略,结合同步旋转坐标系控制技术,实现了并网模式下SSI的解耦控制。利用Matlab/Simulink搭建的模型进行了仿真实验,结果验证了理论分析的正确性和实用性。

新上海一号煤矿软岩回采巷道预裂卸压技术研究

基于新上海一号煤矿软岩巷道支护薄弱的特点,提出了一种新的预裂卸压技术,旨在解决软岩巷道围岩大变形控制难题。该技术主要采用超前预裂卸压为主、NPR锚索协同支护为辅的方式,通过预裂卸压切断采空区顶板与巷道顶板之间的联系,加速顶板垮断,减小悬臂长度及传递至临空巷道顶板的覆岩荷载。同时,采用NPR锚索提前对巷道进行补强加固,确保了沿空巷道在超前应力影响下的稳定性。实地应用表明,采用预裂卸压技术回采巷道围岩变形量得到有效控制,验证了预裂卸压技术的有效性。为软岩巷道稳定性控制提供了一种新的解决方案。

Theory,technology and application of grouted bolting in soft rock roadways of deep coal mines

The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.

基于分离源的高增益矩阵变换器特性分析

针对矩阵变换器(MC)存在的电压传输比限制以及现有升压型MC结构元件多、调制复杂的问题,提出了一种新型的分离源型矩阵变换器(SS-MC)。该结构采用电感、电容和3个二极管替代了双级MC中间的直流链路部件,从而构成分离源升压网络,避免了配置额外的直通占空比。对SS-MC的拓扑结构和分离源网络升压的工作原理进行了分析,阐述了其采用的空间矢量脉宽调制(SVPWM)策略,并针对SVPWM的缺点提出了基于充电预测的模型预测控制(CPB-MPC)策略。仿真和实验结果表明:所提出的SS-MC结构使用常规的SVPWM即可达到较高的电压传输比,但无源元件会存在较大的纹波;使用CPB-MPC策略可以有效抑制纹波,提高MC的输出电能质量。

螺纹钢切分轧制采用控轧控冷工艺生产实践

螺纹钢生产采用切分工艺,可以降低能耗和提高产能,采用控轧控冷工艺又可以显著降低钢坯合金成本,采用三切分工艺与控轧控冷工艺相结合,会增加技术难度。文章介绍了普通螺纹钢产线对传统三切分工艺进行优化后,与控轧控冷工艺相结合,解决了切分后进行飞剪切头控制稳定性差的问题;并通过进行多次控轧控轧工艺试验,摸索出各处关键温度控制范围,稳定了控轧控冷工艺产品的性能,保证产能与效率的同时降低了合金成本。

取水井基坑开挖支护及顶管管道敷设施工技术

自来水厂通常建设在城市郊区或邻近水源等区域,取水井设置在周边环境复杂地域,进出水管道敷设难度相对较大。文章以某水厂扩建工程施工为例,详细介绍了基坑开挖支护以及顶管管道施工质量控制关键技术,为后续类似工程提供参考。

基于分离源矩阵变换器的PMSM无源动态演化控制策略

为了改进传统的永磁同步电机驱动器系统及其PID控制的不足,提出了一种无源动态演化控制策略,并应用于永磁同步电机(permanent magnet synchronous motor,PMSM)和分离源矩阵变换器(split source matrix con-verter,SSMC)中。为打破传统矩阵变换器电压传输比0.866的限制,采用电感、电容和3个二极管代替了双级矩阵变换器中间的支流链路部件,并且证明了分离源网络的升压能力。另外,在矢量控制中,永磁同步电机的转速外环和电流内环都使用了传统PID控制器,但由于PID控制器的参数调节比较困难、控制精度不高、超调量较大和抗干扰能力不强等问题,为此提出了基于动态演化理论和无源理论的控制策略,设计了分离源矩阵变换器和永磁同步电机系统基于互联和阻尼分配(the interconnection and damping assignment,IDA)的无源控制器(passivity-based control,PBC)和动态演化控制器(dynamic evolution controller,DEC)。仿真与实验的结果表明,基于该控制策略的SSMC-PMSM驱动系统能够使永磁同步电机稳定运行在额定转速,并且具有稳定性强、抗干扰能力强和动态响应好等特点。

地下矿山工程井巷掘进爆破技术探究

掘进爆破是地下矿山工程开采的重要一环,爆破技术的应用效果直接关乎地下矿山工程井巷开采效益。因此,简单介绍了地下矿山工程井巷开采背景,以深孔控制预裂爆破技术为例,提出了地下矿山工程井巷掘进爆破技术方案,并对地下矿山工程井巷掘进爆破技术实践要点进行了进一步探究,希望为掘进爆破技术在地下矿山工程井巷中的有效应用提供一些参考。

隧道隧底开挖控制爆破施工技术

隧道拱部围岩超欠挖控制技术已较为成熟,光面爆破等控制爆破技术已广泛应用于隧道建设,但是针对隧底围岩开挖施工,仍采用集中装药的方式进行爆破,超挖情况较为严重。基于以上原因,依托广湛铁路大脊山隧道,对仰拱、底板及中心水沟等小尺寸结构物爆破技术进行探索,通过多循环的爆破参数研究与改进,总结得到了大脊山隧道隧底控制爆破参数,较好地指导了隧道后续施工,仰拱、底板及中心水沟超欠挖得到了较好地控制,减少了隧道施工工序循环时间,保证了隧道提前贯通,综合效益显著。