Mechanochemistry is defined to describe the chemical and physicochemical transformation of substances during the aggregation caused by the mechanical energy. Mechanochemical technology has several ...advantages, such as simple process, ecological safety and the possibility of obtaining a product in the metastable state. It potentially has a prospective application in pollution remediation and waste management. Therefore, this paper aims to give an overall review of the mechanochemistry applications in waste management and the related mechanisms. Based on our study, the modification of fly ash and asbestos-containing wastes (ACWs) can be achieved by mechanochemical technology. Waste metal oxides can be transformed into easily recyclable sulfide by mechanochemical sulfidization. Besides, the waste plastics and rubbers, which are usually very difficult to be recycled, can also be recycled by mechanochemical technology.
This paper presents a method to solve disassembly sequence planning problem. Firstly, disassembly feasibility information graph (DFIG) is presented to describe the product disassembly sequence and ...operation information. Then, disassembly sequence planning problem is mapped onto the DFIG as an optimal path-searching problem. Based on this idea, a genetic algorithm is provided to find out feasible and optimal disassembly solutions efficiently. Finally, a case study, which is used to illustrate the performance of proposed method, is presented.
This paper presents a new 2-D permanent-magnet array for a planar motor, in which the angle between the magnetization directions of any two adjacent magnets is 45°. The harmonic model for flux ...density distribution of the array is solved by the scalar magnetic potential equation and validated by the finite-element method. An analytical model for real-time control is derived by taking the first harmonic of the magnetic flux density distribution. The ignored higher harmonics in z-component of the magnetic flux density distribution is minimized by the genetic algorithm such that the analytical model becomes more accurate. Compared with the well-known Halbach magnet array, the proposed magnet array has lower higher harmonic components and higher z -component of the magnetic flux density, which will reduce the force ripples of the planar motor.
A novel synchronous permanent magnet planar motor (SPMPM) with iron core is proposed. It has higher continuous force compared to the coreless SPMPM. In the novel SPMPM, two sets of windings for ...generating x-direction thrust and y-direction thrust are perpendicularly fixed in the x-direction slots and y-direction slots of a mover core, respectively. For control system development applications, an electromagnetic model is derived and the analytical method for calculating the model parameters is also reported. The model describes an important characteristic of the novel SPMPM that the x-direction thrust and y-direction thrust are independent of each other. To verify the model and the parameter calculation method, the finite element method (FEM) is used for calculating the phase inductances and electromagnetic forces of an example SPMPM. The results from FEM are in good agreement with the results from the analytical equations. It demonstrates the feasibility and credibility of the proposed model and parameter calculation method to a certain extent.
There are still some challenges for the research of assembly planning. One of the reasons is the weakness in effective description of assembly knowledge and information.
An assembly semantic modeling ...approach is presented. Product (assembly) information is described by a three-level semantic abstraction (Concept/Function Level, Structure Level and Part/Feature Level). Semantic object is an abstract description of special product information, in particularly, for assembly relevant information in this proposed study. And by a multi-mapping mechanism supported by Semantic Interpreter and Semantic Dictionary, these objects could retrieve relevant technologic information, e.g. assembly design intention, basic function, assembly hierarchical structure, assembly relations and assembly knowledge, etc., from resource bank.
Based on this approach, an interactive assembly planning system is developed. Product semantic information model could offer much useful information for designer to finish the assembly (process) design and make determination in that process. Therefore, complex and low efficient computation in the design (or planning) process could be avoided.
This paper presents novel overlapping ironless windings for permanent magnet planar motors, which have high winding factors and make full use of the magnetic field of the magnet array in the planar ...motor. A simple analytical model of the planar motors is developed and validated by finite-element method first. Then the winding factors of the ironless windings are derived and used to simplify the analytical model. Furthermore, the design rules of the ironless windings for the planar motor are obtained from the analytical model with winding factors and the ironless windings are optimized for maximum steepness of the planar motor. Compared with the nonoverlapping ironless windings, the novel overlapping ironless windings have a much (up to 25%) larger force with the same copper loss and nearly the same size when the coils of the windings have a large length/width ratio.
Printed circuit board (PCB) disassembly is one of the most difficult tasks in recycling waste electrical and electronic equipment. Analysis of the disassembly mechanics is needed for development of ...disassembly methods for PCB. However, a broad technological gap exists between research on PCB disassembly and industrial applications. One reason is that current research is mainly based on qualitative analyses or experiments without in-depth study of the disassembly mechanics. This paper presents four removal force models for through-hole devices (THD) and surface mount devices (SMD) with a graphical analytical method to determine whether an external force is needed, to calculate the acceleration for removing the components, and to define the acceleration range to disassemble PCB's with various components. The minimum removal forces and/or accelerations for four kinds of conditions are calculated. The results show that THDs can be easily disassembled with small forces or accelerations when no pin is clinched. If the pins are clinched, the removal force increases greatly as the bend angle increases. Small removal forces are required for disassembling various SMDs, but the minimal removal accelerations needed for disassembling SMDs vary greatly with the total wetted length. As the total wetted length increases, the minimum removal force increases while the minimum removal acceleration decreases. The results are used to recommend PCB component disassembly methods. This research will assist with component recovery as well as material separation and provides a quantitative analysis of selection of disassembly methods and the development of disassembly equipment for dismantling waste PCB.
Reuse of plastic IC packages disassembled from printed circuit boards (PCBs) has significant environmental benefits and economic value. The interface delamination caused by moisture diffusion is the ...main failure mode of IC packages during the disassembling process, which greatly reduces the reusability and reliability of disassembled IC packages. Exploring moisture diffusion mechanism is a prerequisite to optimize prebaking processes before disassembling that is an effective way to avoid the interface delamination. To this end, a computational model with variable boundary conditions is developed based on the different combination state of water in IC packages. The distribution characteristics and mechanism of moisture diffusion behavior are analyzed including the humidity distribution field and the relation among baking temperature, water loss rate, and baking time during baking process, and then the results are validated by FEA simulation based on the improved definition of relative moisture concentration. Baking under variable temperature is proposed and compared with the baking process and baking efficiency under constant temperature to find out the optimized baking parameters. Finally, a set of curves which indicate the relation between baking energy consumption and temperature are determined under actual industrial baking experiments, which could be used as references to develop industrial standards for PCB disassembling process.
The two-photon microfabrication method, which has been developed over several years, is a new way to produce the real three-dimension microstructure. And now, this technology is recognized as a ...promising process for the creation of nano- and microscale devices. However, there are still important issues to be settled, one of them is the radial superresolution. The radial superresolution diffraction theory is introduced in the two-photon microfabrication system. This method can improve the radial superresolution of the two-photon microfabrication system. The theoretical analysis of the photosensitive resin is discussed based on the exciting power and concentration of free-radical theory. Experiment results of the two-photon microfabrication method verify the method and show that it can provide weight into the microfabrication system.
► A new 6-DOF's measurement program for X-Y stage based on nine interferometers is proposed. ► The computational algorithm with high accuracy and simple form is derived. ► The direction cosines can ...be determined without an assumed stacked slide model.
In some occasions, high accuracy and real-time 6-degree-of-freedom (6-DOF) displacements should be measured so that the control system can regulate the X-Y stages’ attitude in real time. The accuracy and real-time property of measurement's result depend on not only the sensors itself, but also the accuracy and effort of the computational algorithm using the sensors’ measured data. As the relation between sensors’ measured data and displacements is immensely complex and usually described as strong nonlinear coupling equation when 6-DOF displacements are all considered, computational accuracy and effort are difficult to be ensured simultaneously. This paper designs a 6-DOF displacements’ measurement setup for X-Y stages based on nine interferometers’ additional information, and derives the corresponding computational algorithm. For rotation, its range is usually very small and high accuracy computational results can be obtained using two interferometers’ differential computation; for translation, the closed form solutions without rotational displacement's computational error's transmission are derived by making full use of all additional interferometers’ information, so that the computational accuracy can be ensured. In addition, the algorithm has simple form and doesn’t involve iteration and transcendental function's computation, so that it helps real-time computation. This algorithm can acquire the computational accuracy of 10−15rad and 10−13mm for rotational and translational displacement separately, which can be seen in the simulation result for a lithography's wafer stage.
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