Universal Current-Mode Biquad Employing Dual Output Current Conveyors and MO-CCCA with Grounded Passive Elements

A new universal multiple input multiple output (MIMO) type current-mode biquad employing two dual output current conveyors (DOCCII), one multiple output current controlled current amplifier (MOCCCA) and four passive grounded elements is proposed which can realize all the five basic filtering functions namely, low-pass (LP), high-pass (HP), band-pass (BP), band-stop (BR) and all-pass (AP) in current mode from the same configuration. The centre frequency can be set by the passive elements of the circuit and the quality factor Q0 is electronically tunable through bias currents of the MOCCCA. Therefore, the biquad filter has independent tenability for the and Q0. The active and passive sensitivities of Q0 and are low. The workability of the new configuration has been demonstrated by PSPICE simulation results based upon a CMOS CCII in0.35μm technology.

A comparative study on design standards of screw conveyors in China,Germany,and the USA-Part Ⅱ:Discrete element method

This part of the study aims to evaluate the advantages and disadvantages of technical standards of screw conveyors in China,Germany,and the USA for industrial applications.The source or determination method of empirical coefficients as well as the theoretical foundation of dimensioning-relevant diagrams in these standards is not explicitly documented in the literature.Therefore,instead of less efficient on-site tests,the numerical simulation by discrete element method is conducted.Based on the geometrical and operational designs determined in three standards for horizontal,slightly inclined,and vertical conveyance of three representative bulk solids(barley,lignite,and sand),the potential influencing factors are discussed.With constant particle and contact parameters,the potential deviations caused by particle models are eliminated.Furthermore,the accuracy of power consumption calculation of each standard and the divergence between accessible and required mass flows is comprehensively assessed based on the analysis of simulated outcomes.Two main conclusions are drawn:(1)Particle fall back is barely considered by all three standards and leads to overestimated mass throughput;(2)The decrease in mass throughput caused by an increasing degree of filling can be compensated by slowing down the rotational speed.

A comparative study on design standards of screw conveyors in China,Germany and the USA-PartⅠ:Theoretical calculation and quantitative analysis

Screw conveyors,widely used devices for transporting bulk materials,play an irreplaceable role in the modern industrial system.Despite of their traditional advantages,designers of screw conveyors still heavily rely on their own country's experiments and standards,which are closely related to empirical data.Therefore,the same conveying task often results in different designs.This work aims to compare the design standards of screw conveyors in China,Germany and the USA.Based on related standards acquired from renowned associations in the three countries,the similarities and particularities of these design guidances are compared.With preforming the geometrical and operational designs for horizon-tal,slightly inclined and vertical conveyance of three representative bulk solids(barley,lignite,sand),the advantages and disadvantages of these semi-empirical designs are comprehensively presented.Fur-thermore,the potential influence of empirical coefficients,which are not explicitly documented,are extensively discussed.By analysing all outcomes,the compatibility and applicability of each standard are qualitatively assessed.

Aircraft Observation and Simulation of the Supercooled Liquid Water Layer in a Warm Conveyor Belt over North China

This paper studied a snow event over North China on 21 February 2017,using aircraft in-situ data,a Lagrangian analysis tool,and WRF simulations with different microphysical schemes to investigate the supercooled layer of warm conveyor belts(WCBs).Based on the aircraft data,we found a fine vertical structure within clouds in the WCB and highlighted a 1-2 km thin supercooled liquid water layer with a maximum Liquid Water Content(LWC) exceeding0.5 g kg^(-1) during the vertical aircraft observation.Although the main features of thermodynamic profiles were essentially captured by both modeling schemes,the microphysical quantities exhibited large diversity with different microphysics schemes.The conventional Morrison two-moment scheme showed remarkable agreement with in-situ observations,both in terms of the thermodynamic structure and the supercooled liquid water layer.However,the microphysical structure of the WCB clouds,in terms of LWC and IWC,was not apparent in HUJI fast bin scheme.To reduce such uncertainty,future work may focus on improving the representation of microphysics in bin schemes with in-situ data and using similar assumptions for all schemes to isolate the impact of physics.

Oil-Film Clutch in Soft-Start of Belt Conveyor

The oil film clutch, which is superior in speed adjustment, is capable of being used in the belt conveyor to carry out soft start operation. According to running properties of both belt conveyor and oil film clutch, equations that are used to decide the lubricating oil flow and the number of oil films (i.e. the number of rotating and stationary plates) are deduced theoretically. Also key parameters are provided for the design of the hydraulic system. All these together provide the theoretical basis for the soft start design of the belt conveyor and references for the application of the oil film clutch in similar fields.

基于第二代电流传输器的二阶带通滤波器设计

设计了一种单端输入单端输出的电流模式带通滤波器,核心部件为用三极管设计的第二代电流传输器(CCII)。电路由两个CCII和一些无源器件构成,通过偏置电流控制其中心频率,实现对信号的带通滤波功能。该滤波器提供了更大带宽下的更高电压增益,解决了电压跟随不理想的问题,且具有更低的无源灵敏度,能广泛应用于无线通讯、射频等高频模拟电路中。使用Hspice软件仿真分析并验证了理论设计的准确性和可行性。

Second generation fully differential current conveyor based analog circuits

In this paper, we present a new voltage-mode biquad filter that uses a six-terminal CMOS fully differential current conveyor(FDCCII). The FDCCII with only 23 transistors in its structure and operating at ± 1.5 V, is based on a class AB fully differential buffer. The proposed filter has the facility to tune gain, ωo and Q. A circuit division circuit(CDC) is employed to digitally control the FDCCII block. This digitally controlled FDCCII is used to realize a new reconfigurable fully-differential integrator and differentiator. We performed SPICE simulations to determine the performance of all circuits using CMOS 0.25 μm technology.

A State Variable Method for the Realization of Universal Current-Mode Biquads

A state variable method of converting single-resistance-controlled- oscillators (SRCO), into universal current-mode biquad (offering realizations of all the five standard filter functions namely, low pass, band pass, high pass, notch and all pass) has been highlighted. The workability of the exemplary implementation of the derived current-mode universal biquad has been demonstrated by PSPICE simulation results based upon 0.35 μ m technology. It is expected that the proposed method can be applied to other SRCOs to generate other multifunction filter structures.

KEY TECHNOLOGY OF SEMI-CONTINOUS CONVEYOR SYSTEM IN DEEP SURFACE MINE

The key technology of semi-continuous conveyor system decides the successful using of this system. The key technology includes optimal initial building depth of this system,the crusher moving step and the layout of conveyor system are studied, and their calculating models are built up.

A Plus Type CC-Based Current-Mode Universal Biquad

This paper introduces a current-mode universal biquad circuit using only plus type CCs(current conveyors)(i.e.DVCCs(differential voltage current conveyors)and CCIIs(second generation current conveyors)).The circuit enables LP(low-pass),BP(band-pass),HP(high-pass),BS(band-stop)and AP(all-pass)responses by the selection and/or addition of the input and output currents without any component matching constraints.Moreover the circuit parametersω0 and Q can be set orthogonally adjusting the circuit components.A design example is given together with simulation responses by PSPICE.

A Quadrature Oscillator Based on a New “Optimized DDCC” All-Pass Filter

In this paper, a new voltage-mode (VM), all-pass filter utilizing two second-generation current conveyors and tow differential difference current conveyors (DDCCs) is proposed. This filter uses a number of passive elements grounded capacitor. This structure of filter is used to realize a quadrature oscillator. The proposed circuits employ tow optimized differential difference translinear second generation current conveyers (DDCCII). These structures are simulated using the spice simulation in the ADS software and CMOS 0.18 μm process of TSMC technology to confirm the theory. The pole frequency can be tuned in the range of [11.6 - 39.6 MHz] by a simple variation of a DC current.

Versatile Voltage-Mode Universal Filter Using Differential Difference Current Conveyor

A novel four-input three-output voltage-mode differential difference current conveyor (DDCC) based universal filter is presented. The circuit uses three DDCCs as active elements, two resistors and two capacitors as passive elements. The circuit along with its versatility enjoys the advantage of minimum number of passive elements employment. SPICE simulation results are given to confirm the theoretical analysis. The proposed circuit is a novel addition to the existing knowledge on the subject.

A DVCC-Based Mixed-Mode Biquadratic Circuit

This paper introduces a mixed-mode biquadratic circuit employing DVCCs （differential voltage current conveyors） and grounded passive components. The biquadratic circuit can perform mixed-mode operation selecting the input and output terminals. And the circuit enables LP （low-pass）, BP （band-pass）, HP （high-pass）, BS （band-stop） and AP （all-pass） transfer functions by suitably choosing the input terminals. The circuit parameters o30 and Q can be tuned orthogonally through adjusting the passive components. The biquadratic circuit enjoys very low sensitivities with respect to the circuit components. The achievement example is given together with simulation results by PSPICE.

CCII-Based Inverse Active Filters with Grounded Passive Components

This paper introduces IAFs （inverse active filters） employing CCIIs （second generation current conveyors） and groundedpassive components. The IAFs enable ILP （inverse low-pass）, IBP （inverse band-pass） and IHP （inverse high-pass） characteristics byadding the circuit currents. Additionally, the circuit parameters ω0 and Q can be set orthogonally adjusting the circuit components.The achievement example is given together with simulation results by PSPICE.

Fuzzy-immune control strategy of a hydro-viscous soft start device of a belt conveyor

Considering the control difficulties of a hydro-viscous trol algorithm was derived. A fuzzy-immune PID controller was soft start （HVSS） device of a belt conveyor, a fuzzy-immune con- designed based on immune feedback regulations and adaptability of the fuzzy logic inference. Using MATLAB software, we simulated the controller and compared the HVSS device with a conven- tional PID controller and a fuzzy PID controller. The simulation results show that the controller is not only very reliable as a PID controller, robust and requires only a short adjustment time of fuzzy control, but possesses also capacity of global optimization of the immune algorithm. To verify our theoretical analysis and simulation, a HVSS test-bed was developed. The experimental results demonstrate that the fuzzy-immune PID controller managed to start the belt conveyor softly and to follow an S-shaped curve while the output speed correctly followed the preset speed with only small fluctuations in speed.

Mechanism of hydro-viscous soft start of belt conveyor

The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.

Systematic Synthesis on Pathological Models of CCCII and Modified CCCII

According to the equivalent view for the terminal current-voltage constraint relationship between pathological elements and the various second-generation current-controlled convegors （CCCIIs）, four patholo- gical models for the CCCII are first derived by means of the nodal admittance matrix expansion in this paper. Moreover, 48 new pathological models for the modified CCCII are also synthesized. The derived pathological models for the various CCCIIs are expected to be useful in circuit analysis and synthesis.

Analysis of underground fires in Polish hard coal mines

In the period of the first twenty years after World War II the number of fires in Polish hard coal mines reached annually the value of several thousands of cases. About 80% of fires constituted spontaneous fires. Investigations into the development of new methods of fire hazard prediction and implementation of new methods and means of fire prevention as well as the introduction of prohibition concerning the use of products manufactured of combustible organic materials in underground mine workings re-duced considerably the hazard of underground fire rise. The worked out at the Central Mining Institute (GIG) new method of un-derground fire prediction allows the correct selection of fire prevention means. The introduction into common use of fire-resistant conveyor belts, the main factor giving rise to spontaneous fires, and methods of assessment of their fire resistance eliminated prac-tically the fire hazard. These activities contributed in an efficient way to the reduction of the number of underground fires to a sat-isfactory level.

Study on Semi-Continuous Technology System for Soft Material Stripping in Large Surface Mines

Continuous and semi-continuous mining technology has become the main trend of modern surface mines in the world. According to the deposit characteristics of coal basin in China and Chinese situation,this paper discussed the new semi-continuous technology── shovel - transfer wagon-belt conveyor and its application prospect in large surface coal mines in China.

Dynamic characteristics of conveyor belts

The dynamic characteristics of a belt conveyor are determined to a large extent by the properties of the belt. This paper describes experiments designed to establish the dynamic properties of belting material. The dynamic elastic modulus, viscous damping and rheologicat constants of the belt were measured. Several properties were studied as a function of the tensile loading on the belt. These included longitudinal vibration, the natural vibration frequency in the transverse direction and the response to an impulse excitation. Vibration response was observed under several different excitation frequencies. Most of these properties have not been tested previously under conditions appropriate for the ISO/DP9856 standard. Two types of belt were tested, a steel reinforced belt and a fabric reinforced belt. The test equipment was built to provide data appropriate for designing belt conveyors. It was observed that the stress wave propagation speed increased with tensile load and that tensile load was the main factor influencing longitudinal vibrations.