A novel heuristic optimization method: charged system search

This paper presents a new optimization algorithm based on some principles from physics and mechanics, which will be called Charged System Search (CSS). We utilize the governing Coulomb law from electrostatics and the Newtonian laws of mechanics. CSS is a multi-agent approach in which each agent is a Charged Particle (CP). CPs can affect each other based on their fitness values and their separation distances. The quantity of the resultant force is determined by using the electrostatics laws and the quality of the movement is determined using Newtonian mechanics laws. CSS can be utilized in all optimization fields; especially it is suitable for non-smooth or non-convex domains. CSS needs neither the gradient information nor the continuity of the search space. The efficiency of the new approach is demonstrated using standard benchmark functions and some well-studied engineering design problems. A comparison of the results with those of other evolutionary algorithms shows that the proposed algorithm outperforms its rivals.     

Engineering design optimization using chaotic enhanced charged system search algorithms

The charged system search as a recently developed meta-heuristic algorithm has been successfully utilized for optimum design of different examples. In addition, the fields of forces model provides a means to enhance the algorithm, and this results in the enhanced charged system search (ECSS). This paper utilizes positive features of the chaos in the ECSS algorithm to optimize engineering design problems. Simulation results and comparisons based on various well-known mechanical and engineering design problems show the efficiency of the present algorithm.     

Mechanism of interaction of magnetic fields with biological systems

A review is presented of the known mechanisms by which magnetic fields can interact with biological systems. The basic equations for exerting forces by both AC and DC magnetic fields on charged particles and dipoles are reviewed. Examples are given that allow order-of-magnitude estimates of the induced current densities and forces to be obtained. These estimates are compared with values known to induce measurable changes in the behavior of biological systems     

Organic Bioelectronics: From Functional Materials to Next-Generation Devices and Power Sources

Conjugated polymers (CPs) possess a unique set of features setting them apart from other materials. These properties make them ideal when interfacing the biological world electronically. Their mixed electronic and ionic conductivity can be used to detect weak biological signals, deliver charged bioactive molecules, and mechanically or electrically stimulate tissues. CPs can be functionalized with various (bio)chemical moieties and blend with other functional materials, with the aim of modulating biological responses or endow specificity toward analytes of interest. They can absorb photons and generate electronic charges that are then used to stimulate cells or produce fuels. These polymers also have catalytic properties allowing them to harvest ambient energy and, along with their high capacitances, are promising materials for next-generation power sources integrated with bioelectronic devices. In this perspective, an overview of the key properties of CPs and examination of operational mechanism of electronic devices that leverage these properties for specific applications in bioelectronics is provided. In addition to discussing the chemical structure–functionality relationships of CPs applied at the biological interface, the development of new chemistries and form factors that would bring forth next-generation sensors, actuators, and their power sources, and, hence, advances in the field of organic bioelectronics is described.     

Magnetic field tracking with MCNP5

With the introduction of continuous-energy heavy charged particle transport in MCNP5, the need for tracking charged particles in a magnetic field becomes increasingly important. Two methods for including magnetic field effects on charged particles are included in the proton transport version of the code. The first technique utilises transfer maps produced by the beam dynamics simulation and analysis code COSY INFINITY. This method is fast and accurate; however, its use is limited to void cells only and to ensembles of particles with a fairly small energy spread. The second technique, particle ray tracing, is based on an algorithm adopted from the MARS transport code. This method can be applied to both void and material cells and is valid over a very large range of particle energies. Results from tracking particles in a quadrupole 'identity lens' using the two techniques are compared.     

Improved Particle Image Velocimetry Through Cell Segmentation and Competitive Survival

A new model of cell segmentation and competitive survival (CSS) is integrated into the standard techniques of particle image velocimetry (PIV). First, a set of initial interrogation fields is identified in the images, and the cells are defined in the field by cross correlation. Each cell is then segmented into smaller groups of matching points with different degrees of correlation. These subcells compete with each other to define the properties of the cell; the winner, in turn, competes with the other cells. Finally, the velocity vector of the field is defined as the displacement of the winning cell's centroid between frames. The algorithm is applied to some real and synthetic particle images, and its results are compared to particle correlation velocimetry and recursive PIV approaches. These experiments demonstrate that the CSS approach is effective and practical.     

Novel magnetic tips developed for the switching magnetization magnetic force microscopy

Using micromagnetic calculations we search for optimal magnetic properties of novel magnetic tips to be used for a Switching Magnetization Magnetic Force Microscopy (SM-MFM), a novel technique based on two-pass scanning with reversed tip magnetization. Within the technique the sum of two scans images local atomic forces and their difference maps the local magnetic forces. The tip magnetization is switched during the scanning by a small magnetic field. The technology of novel low-coercitive magnetic tips is proposed. For best performance the tips must exhibit low magnetic moment, low switching field, and single-domain state at remanence. Such tips are equipped with Permalloy objects of a precise shape that are defined on their tilted sides. We calculate switching fields of such tips by solving the micromagnetic problem to find the optimum shape and dimensions of the Permalloy objects located on the tips. Among them, hexagon was found as the best shape for the tips.     

CIFTER: automated charge-state determination for peptide tandem mass spectra

Tandem mass spectrometry (MS/MS) has become a common and useful tool for analyzing complex protein mixtures. Database search programs are the most popular means for peptide identification from MS/MS spectra. However, estimations of charge states of peptide MS/MS spectra obtained from low-resolution mass spectrometers have not been reliable. They require repetitive database searches and additional analyses of the search results. We propose here an algorithm designed to reliably differentiate doubly charged spectra from triply charged ones. We conducted a rigorous analysis of various spectral features and their effects. We employed the distinguishing features found in our analysis and developed a classifier for multiply charged spectra using a machine learning approach. The test on various data sets showed that our method could be successfully applied independent of experimental setup and mass instrument. This algorithm can be used to prefilter spectra so that only reasonably good spectra are submitted to database search programs, thereby saving considerable time. The software for MS/MS charge-state determination, which we named "CIFTER", is available at a website http://prix.uos.ac.kr/sifter/cifter.     

Non-dominated ranked genetic algorithm for a multi-objective mixed-model assembly line sequencing problem

The increasing market demand for product variety forces manufacturers to design mixed-model assembly lines (MMAL) on which a variety of product models similar to product characteristics are assembled. This paper presents a method combining the new ranked based roulette wheel selection algorithm with Pareto-based population ranking algorithm, named non-dominated ranking genetic algorithm (NRGA) to a just-in-time (JIT) sequencing problem when two objectives are considered simultaneously. The two objectives are minimisation the number of setups and variation of production rates. This type of problem is NP-hard. Various operators and parameters of the proposed algorithm are reviewed to calibrate the algorithm by means of the Taguchi method. The solutions obtained via NRGA are compared against solutions obtained via total enumeration (TE) scheme in small problems and also against four other search heuristics in small, medium and large problems. Experimental results show that the proposed algorithm is competitive with these other algorithms in terms of quality and diversity of solutions.     

Static and dynamic forces on a permanent magnet levitating between superconducting surfaces

A charged magnetic microsphere (radius 100 µm) is levitating inside a superconducting niobium capacitor. Because of its charge of about 1 pC, oscillations about the equilibrium position can be excited and detected electrically. The properties of this oscillator are investigated in order to study the static and dynamic forces of magnetic levitation. We find resonance frequencies between 200 Hz and 600 Hz. The resonance frequency and the damping are amplitude dependent due to nonlinear return forces and nonlinear friction, respectively. At small amplitudes the Q value is about 10⁶ in vacuum. A dc field can be applied to change the equilibrium position and consequently the resonance frequency. From the data the spatial dependence of the static force and of the dynamic stiffness can be determined and an empirical relation between both is established. Quite often, we find a hysteretic behavior of the static force whereas the stiffness is a reversible function of the position. Amplitude dependent damping is observed both in the decay of the free oscillations and in the dependence of the amplitude of the forced oscillations on the driving force.     

Investigation of contact stresses of a rotating cam by a digital photoelastic method

The maximum contact shear stresses (MCSS) and their locations of a rotating cam during rise and at a specific rotation speed were sought by a self-developed digital phototelastic system with added functions of syncronous trigger and continuous image taking. Also found were the MCSS of a camduring rise under static state. The difference between the dynamic and static states were compared and investigated.     

Superconducting cylinder in a static longitudinal magnetic field

A study of the calculation of the magnetic field forces acting on a superconducting cylinder in a longitudinal magnetic field is reported. A computation algorithm and the results of field calculation by means of the boundary integral method, taking account of the cylinder edge singularity, are presented. The method makes it possible to compute the forces pressing the cylinder with a relative error below 1%     

Optimal cutting conditions in turning of particulate metal matrix composites based on experiment and a genetic search model

The results of an experimental study concerned with the evolution of cutting forces, tool wear and surface roughness, as functions of time when turning the particulate metal matrix composite A356/20/SiCp-T6 are presented. Inserts with polycrystalline diamond (PCD) were tested. Cutting forces were measured using a piezoelectric dynamometer. The wear type was identified and its evolution with cutting time was measured. To model the phenomena a hybrid technique based on an evolutionary search over the design space defined by the experimental results is considered. Optimal cutting conditions are searched using a genetic algorithm based on an elitist strategy. The chromosomes composed by random keys represent cutting conditions defined according to a temporal scale.     

Characterization of magnetic forces by means of suspended particles in paramagnetic solutions

A new technique, whereby the so-called "iso-directional-force lines" may be illustrated directly, is proposed. The method is based on the levitation forces acting on a particle immersed in paramagnetic fluid in nonhomogeneous magnetic field. An ordered set of capillaries, each containing a small particle suspended in the fluid, may be used to depict the iso-directional-force lines by the equilibrium positions of the particles. Once the field is mapped (by a selected standard system), its characteristics are known, with respect to any other fluid particle combinations. The latter is of significance for research and technology.     

导电聚合物腐蚀防护涂层的制备与改性技术研究进展

我国海洋工程装备制造业正处在生存与发展的关键阶段,防腐涂层是降低基材腐蚀速率、提升其服役寿命最有效的方式之一。导电聚合物涂层由于其绿色环保、制备简单等优点及独特的导电与防腐机制,使其在金属腐蚀防护领域得到了广泛的应用。本文归纳总结了导电聚合物涂层的防腐机制,介绍了采用化学氧化和电化学合成两种方法制备导电聚合物涂层的现状,重点阐述了导电聚合物涂层的掺杂改性、共聚改性、分层设计3种改性技术对涂层耐蚀性能的提升效果,最后提出了导电聚合物涂层在腐蚀防护领域可能存在的研究热点和发展趋势。     

Two dogmas of charged particle optics

Designs of charged particle optical systems are invariably based on two assumptions: (1) The existence of a reference trajectory and (2) midplane symmetry. The reference trajectory is taken to be the path of a charged particle with certain specified initial conditions. Conditions which break the continuity of the reference trajectory are misalignments of magnets, excess horizontal field in a bending magnet, and vertically bending field in a horizontally bending magnet.Even if midplane symmetry is violated in a magnetic system it is usually respected in each magnetic element. Violation of midplane symmetry in a bending magnet occur if the field is not symmetric about the magnetic midplane.Equations of motion have been worked out for the case where both the above mentioned conditions are violated. Solutions have been produced and incorporated into the first- and second-order formalism of charged particle optics.     

Real-parameter quantum evolutionary algorithm for economic load dispatch

A novel real-parameter optimisation algorithm called the 'real-parameter quantum evolutionary algorithm' is presented. The algorithm pieces together the ideas from evolutionary algorithms (EA) and quantum computing to provide a robust optimisation technique that can be utilised to optimise highly constrained non-linear real-parameter functions. Quantum bits have immense representational power due to their being in superposition of all the basic states at the same time. New quantum operators designed in this work enable the search to effectively handle the twin objectives of exploitation and exploration. This enables the search to be pursued with small population sizes, thereby speeding up the search process and also ensuring that there is no problem of premature convergence that often plagues pure EA implementations. The power of the proposed algorithm is demonstrated by solving the economic load dispatch (ELD) in power systems. ELD is to find the optimal loadings on the generators so as to achieve minimum operating cost while satisfying various system and unit-level constraints. The proposed method has been applied to standard load dispatch problems reported in the literature including the IEEE 30 bus system, IEEE 57 bus system and a 110-generator problem, and its performance has been compared with the results obtained by other methods. The results adequately demonstrate the enhanced search power of the proposed algorithm in terms of obtaining better solutions and provide motivation for its application to other real-parameter optimisation problems in power systems.     

Use of Texture-Dependent Ultrasonic Parameter as Indicator of Degradation of Hot-Rolled Thin-Sheet Steel Under Uniaxial Tension

Journal of Nondestructive Evaluation - Centrifugal pumps (CPs) are mainly composed of impeller and bearings. The operation of the CPs is disturbed if any of its components is faulty. Bearings...     

磁性材料在磁场中所受磁场力的数学模型

本文探讨建立表征磁性材料在磁场中所受磁场力数学模型的方法。首先 ,介绍电磁场理论中基于虚功原理导出的磁场力的一般数学表达式 ;然后 ,基于电力设备磁路的对称性给出其磁场力简化数学模型 ;最后 ,给出磁准静态场和正弦交变电磁场条件下的铁磁质所受磁场力的数学模型。这些数学模型的建立为定性和定量分析大型电力变压器铁心及其它电力设备磁路由于磁性材料中存在涡流而产生的振动和噪声奠定了基础。     

An ant colony system-based hybrid algorithm for square root concave cost transhipment problems

Concave cost transhipment problems are difficult to optimally solve for large-scale problems within a limited period of time. Recently, some modern meta-heuristics have been employed for the development of advanced local search based or population-based stochastic search algorithms that can improve the conventional heuristics. Besides these meta-heuristics, the ant colony system algorithm is a population-based stochastic search algorithm which has been used to obtain good results in many applications. This study employs the ant colony system algorithm, coupled with some genetic algorithm and threshold accepting algorithm techniques, to develop a population based stochastic search algorithm for efficiently solving square root concave cost transhipment problems. The developed algorithms are evaluated with a number of problem instances. The results indicate that the proposed algorithm is more effective for solving square root concave cost transhipment problems than other recently designed local search based algorithms and genetic algorithm.