This paper introduces a new window comparator circuit utilizing a new current conveyor and two diodes, operable at ±1.25 V and capable of accurately detecting the voltage windows. Another modified ...circuit with distinct binary levels suited for automatic control applications is also suggested. Exhaustive simulation results showing detection of windows, as small as 50 mV and as high as 1 V, are included. Comparisons are further drawn with the traditional operational amplifier based circuit and the new circuit is found to benefit from the use of current-mode active element, namely, Extra-X Current Controlled Current Conveyor. The proposed theory is well supported through simulation results.
Due to increasing demands for ensuring the safety and reliability of a system, fault detection (FD) has received considerable attention in modern industries to monitor their machines. Bulk materials ...are transported worldwide using belt conveyors as an essential transport system. The majority of conveyor components are monitored continuously to ensure their reliability, but idlers remain a challenge to monitor due to the large number of idlers (rollers) distributed throughout the working environment. These idlers are prone to external noises or disturbances that cause a failure in the underlying system operations. The research community has begun using machine learning (ML) to detect idler's defects to assist industries in responding to failures on time. Vibration and acoustic measurements are commonly employed to monitor the condition of idlers. However, there has been no comprehensive review of FD for belt conveyor idlers. This paper presents a recent review of acoustic and vibration signal-based fault detection for belt conveyor idlers using ML models. It also discusses major steps in the approaches, such as data collection, signal processing, feature extraction and selection, and ML model construction. Additionally, the paper provides an overview of the main components of belt conveyor systems, sources of defects in idlers, and a brief introduction to ML models. Finally, it highlights critical open challenges and provides future research directions.
This brief presents a comprehensive study on a particular kind of conveyor called second-generation voltage conveyor (VCII). This building block is based on voltage conveying concept and is the dual ...of second generation current conveyor (CCII). It is shown that VCII is a very useful block in those configurations where CCII is limited, in terms of number of active blocks. The results of this brief are helpful in choosing the best building block between CCII and VCII for each specific application. Finally, for the first time, the CMOS implementation of VCII is also presented. Simulation results with PSPICE using 0.35-μm CMOS technology and supply voltage of ±1.65 V are given to approve the theory.
Belt conveyors play an important role in the dry bulk material handling process. Speed control is a promising method of reducing the power consumption of belt conveyors. However, inappropriate ...transient operations might cause risks like material spillage away from the belt conveyor. The unexpected risks limit the applicability of speed control. Current studies on speed control mainly focus on designing energy models of belt conveyors or building control algorithms of variable speed drives, while rare researchers take into account the risks in transient operations and the dynamic performance of belt conveyors under speed control. The paper proposes an Estimation-Calculation-Optimization (ECO) method to determine the minimum speed adjustment time to ensure healthy transient operations. The ECO method is composed of three steps and takes both risks in transient operations and the conveyor dynamics into account. In the Estimation step, an estimator is built to approximate the permitted maximum acceleration by treating the belt as a rigid body. Taking the belt's visco-elastic property into account, the Calculation step computes the conveyor dynamics by using a finite-element-method. With respect to the risks in transient operations, the Optimization step improves the conveyor's dynamic behaviors and optimizes the speed adjustment time. A case of a long belt conveyor system is studied and the ECO method is applied. The secant method is also used to improve the optimization efficiency. According to the experimental results, the ECO method is successfully used to determine the minimum speed adjustment time to ensure healthy transient operations, including both the accelerating and the decelerating operations. With the suggested adjustment time, unexpected risks are avoided and the belt conveyor shows an appropriate dynamic behavior. Accordingly, the ECO method ensures healthy transient operations and improves the applicability of speed control with the consideration of the potential risks and the conveyor dynamics.
Display omitted
•Speed control is used to improve the energy efficiency of belt conveyors on handling bulk solid materials.•The ECO method is proposed to determine the minimum speed adjustment time to ensure a healthy transient operation.•The ECO method improves the applicability of speed control of belt conveyors.•The optimization process is defined as a process of finding the root of function.•The iteration method is used to improve the computation efficiency.
•A framework of integrated maintenance decision making is prompted.•Reliability and condition monitoring data are integrated and interacted.•Threshold value of a monitoring parameter varies in the ...framework.•The framework results in more accurate maintenance decision making.
Belt conveyor systems are widely utilized for continuous transport of bulk materials. Maintenance activities are essential to ensure the reliability of belt conveyor systems. Conventional diagnosis decision is achieved based on empirical constant thresholds. The Challenge of this study is to propose a framework of integrated maintenance decision making for belt conveyor idlers. Information from operational conditions, reliability estimation of idlers and condition monitoring data are integrated for accurate decision making. Innovatively, in the proposed framework threshold of the monitoring parameter can vary according to real time operational conditions and reliability estimation results. A simulation study is presented to demonstrate the effectiveness of framework. Simulation results show that the framework can result in more accurate maintenance decision making compared to conventional approaches.
Display omitted
Display omitted
•Estimation-Calculation-Optimization method applicable to consider conveyor dynamics.•The Delft Systems Approach applicable to model speed-controlled belt conveyor system.•A control ...algorithm takes time-overlapping conflicts into account for speed control.•Considerable energy saving can be achieved by applying active speed control.
Belt conveyor systems play an important role in dry bulk material handling. Speed control is a promising solution to improve energy efficiency of belt conveyors. Active speed control algorithm was proposed for application on individual belt conveyor. This work investigates its application on a multi-belt conveyor system. The Delft Systems Approach is used to model both operation and control systems. The dynamic behaviour of conveyor belts during transient state is taken into consideration. A Simulation study of a dual-belt conveyor system is carried out to verify the proposed active speed control algorithm. Simulation results show that during eight hours’ operation, active speed control can achieve hourly average energy saving of 16.21% compared with constant speed operation scenario. The simulation study verifies that active speed control on belt conveyor systems leads to more sustainable operation.
A new low-voltage low-power class-AB second generation voltage conveyor (VCII) is presented. The proposed circuit is based on an improved class-AB flipped voltage follower (FVF) designed by adding a ...simple negative feedback loop to the conventional class-AB circuit. This modification ensures high current drive capability of at least 2 mA for both falling and rising edges of input signal along with very low 2-mΩ output impedance and high accuracy. Benefiting from the new class-AB FVF, the proposed VCII features a very simple implementation, extremely low impedance at Y and Z terminals (2 mQ), high impedance at X terminal (370 kQ) and high accuracy in current and voltage conveying (99% and 98%, respectively). Moreover, it exhibits current drive capability 117.6 times larger than its bias current (17 μA). The circuit occupies 381.5 μm × 197 μm area. The application of the proposed VCII as a voltage integrator is also presented. Simulation results using PSpice and 0.35-μm CMOS technology with ±1.65-V supply voltage are provided to demonstrate the presented theory. A comparison with the literature is also provided.
This article offers to those pursuing new research in pneumatic conveyance an extensive, deep-background review of the current state of pneumatic conveying around the world. This synopsis of the ...knowledge presented is designed to identify for researchers gaps in the research field that still need to be addressed.
Comparison of Flow Patterns with and without electrostatics present. Display omitted
PDF
