Optimization of CMOS repeater driven interconnect RC line using genetic algorithm

In this work, optimization of complementary metal oxide semiconductor (CMOS) repeater driven interconnect resistive-capacitive (RC) line is carried out using genetic algorithm (GA). This work is aimed at powerdelay- product (PDP) minimization of RC interconnect at 180 nm technology node. The algorithm simultaneously optimizes the values of supply voltage, number of repeaters and repeater width for delay and PDP minimization. The accuracy of results obtained is verified by simulations from Cadence virtuoso tool. For delay minimization, comparison of GA results with previous results of the literature shows an improvement of 44.4% in the value of the optimal number of repeaters required. This improvement is obtained by increasing the repeater size, which also increases power dissipation, so a tradeoff has also been achieved in terms of PDP minimization. The comparison of PDP results obtained in this work, with the results at 70, 100, and 130 nm technologies from literature shows improvement in optimal number of repeaters required. The results of algorithm and simulations are in good agreement and demonstrate the validity of proposed algorithm.     

Numerical study on water depth effects on hydrodynamic forces acting on berthing ships

Due to the restrictions of ports, maneuverability of berthing ships will be affected significantly by water depth. In the present study, numerical simulation of the berthing maneuver of a ship with prescribed translational motion is performed by solving the Reynolds-averaged Navier-Stokes (RANS) equations based on overset grid, and the effects of the quaywall and freesurface are taken into consideration. To validate the present numerical method, comparison is performed between our results and the other results or measurements. It is found that the agreement is significantly better than that resulting from previous CFD-based approach. Subsequently, the effects of various water depths are investigated to evaluate their influences on hydrodynamic forces. The present results can provide helpful guidance on safe maneuvering for vessels’ berthing and fender system design in quays.     

Hierarchical control strategy of trajectory tracking for intelligent vehicle

In order to track the desired trajectory for intelligent vehicle, a new hierarchical control strategy is presented. The control structure consists of two layers. The high-level controller adopts the model predictive control (MPC) to calculate the steering angle tracking the desired yaw angle and the lateral position. The low-level controller is designed as a gain-scheduling controller based on linear matrix inequalities. The desired longitudinal velocity and the yaw rate are tracked by the adjustment of each wheel torque. The simulation results via the high-fidelity vehicle dynamics simulation software veDYNA show that the proposed strategy has a good tracking performance and can guarantee the yaw stability of intelligent vehicle.     

A generalized self-consistent model for interfacial debonding behavior of fiber reinforced rubber matrix sealing composites

This paper presents an experimental and numerical study of short-fiber-reinforced rubber matrix sealing composites(SFRC). The transverse tensile stress-strain curves of SFRC are obtained by experiments. Based on the generalized self-consistent method, a representative volume element(RVE) model is established, and the cohesive zone model is employed to investigate the interfacial failure behavior. The effect of interphase properties on the interfacial debonding behavior of SFRC is numerically investigated. The results indicate that an interphase thickness of 0.3 μm and an interphase elastic modulus of about 502 MPa are optimal to restrain the initiation of the interfacial debonding. The interfacial debonding of SFRC mainly occurs between the matrix/interphase interface,which agrees well with results by scanning electron microscope(SEM).     

Absolute quantum efficiency calibration of analog detectors with twin photon current

Correlated photon is exploited as a tool for absolute quantum efficiency calibration of photon detectors working in the photon-counting regime. We extend the method from photon-counting regime to the absolute calibration of analog regime photon detectors. A revised calibration module is proposed based on balance detection and fluctuation restrictions conditions applied to analog photon detectors. An absolute calibration experimental system is established. This method shows a relative standard uncertainty of 2.1% and a relative deviation of 1% compared with those of the typical photomultiplier quantum efficiency.     

Solving service selection problem based on a novel multi-objective artificial bees colony algorithm

Service computing is a new paradigm and has been widely used in many fields. The multi-objective service selection is a basic problem in service computing and it is non-deterministic polynomial (NP)-hard. This paper proposes a novel multi-objective artificial bees colony (n-MOABC) algorithm to solve service selection problem. A composite service instance is a food source in the algorithm. The fitness of a food source is related to the quality of service (QoS) attributes of a composite service instance. The search strategy of the bees are based on dominance. If a food source has not been updated in successive maximum trial (Max Trial) times, it will be abandoned. In experiment phase, a parallel approach is used based on map-reduce framework for n-MOABC algorithm. The performance of the algorithm has been tested on a variety of data sets. The computational results demonstrate the effectiveness of our approach in comparison to a novel bi-ant colony optimization (NBACO) algorithm and co-evolution algorithm.     

Methods for calculating intervals of reconstructed results in traffic accidents with different types of interval traces

In order to obtain more effective uncertainty analysis methods for analyzing uncertainty of a reconstructed result in a traffic accident with different types of interval traces, three new methods are proposed. The first method is named as sub-interval perturbed method, it is used for calculating the binary interval of the reconstructed result in an accident with binary interval traces, and it can overcome the interval extension problem well. The second method is based on interval arithmetic and the first method, it is used for calculating the ternary interval of the accident reconstruction result in an accident with ternary interval traces, and the most probable value of the reconstructed result is a number. The basic idea of the third method is the same as that of the second method, it is used for calculating the ternary interval of the accident reconstruction result in an accident with mixed interval traces, and the most probable value of the reconstructed result is an interval. All methods are demonstrated and validated by numerical cases. The results show that all methods are feasible and practical. Finally, a true vehicle-motorcycle accident is given, in which the braking distance of vehicle, and the throw distances of driver and motorcycle are all binary interval traces. The accident is reconstructed by the software PC-Crash, and the interval of impact velocity is analyzed. The interval of the velocity is [55.7, 64.3] km/h. This interval result is more objective than a single number.     

Optimal allocation of fleet’s spare parts for system reliability

Allocation of fleet’s spare parts is rarely studied due to its complexity. However, this task is extremely important because the warship’s service level highly relies on the maintenance logistics’ level. In this study, the readiness ratio is proposed as a critical index in measuring the system’s reliability. A well-established mathematical model adopting the optimization method of spare part allocation is also introduced. The objective is to minimize the number of each spare part while satisfying the fleet’s system reliability. The fault tree analysis (FTA) is applied to analyze the system’s failure logic and stratify the units on ship. As a result, the strategy of spare part sharing can be introduced in detail. The solution algorithm is developed, and the simulation experiments to obtain the key parameters are conducted. The proposed model and algorithm are applied to an actual fleet of two warships, and results show that the method above is feasible and can be directly applied into practice.     

Pedestrian crosswalk overflow violation in China: Characteristics and countermeasure

The phenomenon that pedestrians do not walk in the crosswalk during pedestrian green is defined as overflow violation, which is illegal but common. Broadly varying crossing positions at far-side cross-section may result in widely distributed conflict points with left-turning and right-turning vehicles, which may cause the occurrence of severe conflicts. This paper proposes a model to estimate the overflow pedestrians’ crossing positions at the far-side cross-section of signalized crosswalk, which enables us to better understand pedestrian overflow violation behavior and finally facilitate their safety. After analysis, the intersection geometry and destination are determined as the critical factors causing pedestrians to overflow. And then, Weibull distribution is employed to describe the stochastic characteristics of overflow pedestrians’ crossing position distribution at the far-side cross-section. A crossing position distribution model which takes the crosswalk length, width and distance between crosswalk and destination into account is developed. The established model is validated by comparing the observed pedestrian crossing positions with the estimated crossing positions. The validation results suggest that the established model is capable of being adopted to estimate the overflow pedestrians’ crossing positions at far-side cross-section. Based on the model, countermeasure for overflow violation can be put forward to prevent pedestrians from walking outside the crosswalk.     

Research of order allocation model based on cloud and hybrid genetic algorithm under ecommerce environment

For massive order allocation problem of the third party logistics (TPL) in ecommerce, this paper proposes a general order allocation model based on cloud architecture and hybrid genetic algorithm (GA), implementing cloud deployable MapReduce (MR) code to parallelize allocation process, using heuristic rule to fix illegal chromosome during encoding process and adopting mixed integer programming (MIP) as fitness function to guarantee rationality of chromosome fitness. The simulation experiment shows that in mass processing of orders, the model performance in a multi-server cluster environment is remarkable superior to that in stand-alone environment. This model can be directly applied to cloud based logistics information platform (LIP) in near future, implementing fast auto-allocation for massive concurrent orders, with great application value.