Cyber physical systems for predictive production systems

As disruptive technologies like Industry 4.0 and Internet of Things advance at a breakneck speed, modern manufacturing is ready to embrace the systematic deployment of predictive production systems. The predictive production system is an intelligent manufacturing system where networked assets are equipped with self-awareness to predict, root cause, and reconfigure faulty events automatically. Cyber physical systems are one of the core enabling technologies within which information from all the related perspectives are analyzed and interconnected between physical factory floor and the cyber computational space. It intertwines with smart analytics to comprehend invisible issues for rapid decision making. In this paper, a systematic approach is proposed on how cyber physical systems can be applied to predictive production systems to inject resilience and interoperability so that the productivity of manufacturing can be optimized.     

On the influence of deformation rate and cooling media on the static strain aging of a warm-rolled low carbon steel

An investigation was performed on the static strain aging behavior of warm-rolled low carbon steel during a nearly 1-year aging period, from the view point concerning with influence of changing the deformation speed and cooling media. Mechanical response of the examined material during aging period was evaluated through variations occurred in strength and hardness of the warm-deformed steel. It was shown that changing the rolling speed as well as cooling rate, may result in the occurrence of different metallurgical phenomena, consequently altering the aging kinetics of the material. It was also found that by increasing rolling speed, an increase in the value of hardness and UTS takes place, while changing the cooling rate to a higher value can cause a more considerable variation in the mechanical behavior of warm-rolled samples throughout the aging period. From the industrial point of view, the experiments conducted in this work is in agreement with the practical conditions of high temperature rolling processes with long interpass times, such as Steckel rolling process.     

An experimental investigation on liquefaction potential and post-liquefaction shear strength of impounded fly ash

Liquefaction resistance and post-liquefaction shear strength of impounded Class F fly ash are investigated using laboratory experiments. The study was aimed to evaluate liquefaction potential of a 45 ha impoundment proposed as a base for a utility monofill. The evaluation included cyclic triaxial tests performed on reconstituted fly ash specimens with various densities at different confining stresses and cyclic stress ratios representative of the impounded material and the seismic environment. The results are presented in the form of design charts. Post-liquefaction strengths were measured by reconsolidating the specimens at the initial effective confining stress and performing consolidated undrained triaxial tests. The measured cyclic strength was compared with the seismically induced stresses in the profile using a one-dimensional wave propagation method. The cyclic loadings imposed on the ash by the design earthquakes were found to be lower than the measured cyclic strength of the material. The post liquefaction shear strengths showed some scatter; however, they were typically higher than the initial shear strengths before exposure of the material to cyclic load.     

Performance Analysis of Generic Amplify-and-Forward Cooperative Networks over Asymmetric Fading Channels

In this paper, we analyze the performance of multi-hop multi-branch amplify-and-forward (AF) networks over generalized fading channels. Using the moment generating function (MGF)-based approach, we develop general expressions for the outage probability and symbol-error rate (SER) performance of the system with maximal ratio combining (MRC) receiver. The MGF-based approach relies on numerical integration. To gain insights into system performance, we therefore investigate the asymptotic outage and SER performance of the system with MRC and selection combining (SC) receiver at the destination. In particular, we develop the asymptotic statistics of the end-to-end signal-to-noise ratio (SNR) of an AF multi-hop link. We further derive the cumulative density function of the sum of the individual end-to-end SNRs, received from different diversity paths for MRC receiver. We also study the power allocation problem in a multi-hop multi-branch system with MRC receiver. In generalized Gamma fading environments, we seek to find the power allocation strategy that maximizes the SNR at the destination subject to a total power constraint. By means of simulations, we validate our theoretical developments and verify the efficiency of our proposed power allocation in improving the received SNR compared to a generic cooperative system with no power allocation. We also conclude that our asymptotic expressions for the outage probability and SER match the simulations very well in medium-to-high-SNR regime.     

Influence of deformation path change on static strain aging of cold rolled steel strip

Effect of deformation path change on the static strain aging of low carbon steel was studied in this work. In the first stage, strip samples were subjected to cold rolling processes under different paths with the same total reduction in thickness while the deformation behaviors of the rolled samples were also evaluated using a mathematical analysis. Then, cold-rolled strips were aged in room temperature up to 45?days while hardness and tensile evaluations were performed to assess the mechanical properties of the as-rolled and the aged samples. Finally, the influence of rolling pass schedule on the subsequent strain aging phenomenon was investigated by means of the experimental results and the predictions. The results indicate that rolling path schedule significantly changes plastic strain and residual stress distributions. Furthermore, the kinetics of aging phenomenon also varies after different rolling paths where a schedule containing two-pass reverse layout may result in the fastest aging kinetics.     

Linear Pre-coding in MIMO–CDMA Relay Networks

Our aim in this paper is to define a novel beamforming approach in wireless multiple-input-multiple-output (MIMO) code-division-multiple-access (CDMA) relay networks, which involves communication between multiple source-destination pairs. It is assumed that full channel state information of source-relay and relay-destination channels are available. Our design consists of a two-step amplify-and-forward protocol. The first step includes signal transmission from the sources to the MIMO relay, and the second step contains transmitting a version of the linear precoded signal to the destinations. Beamforming is investigated only in MIMO-relay node to reduce end user’s hardware complexity and save the computational power. Accordingly, the optimization problem is defined to find the MIMO relay beamforming coefficients that minimize total relay transmit power by keeping the signal-to-interference-plus-noise ratio (SINR) of all destinations above a certain threshold value. It is shown that such optimization problem is a non-convex quadratically constrained quadratic programming, which is NP-hard in general. However, by relaxing this problem to a semi-definite programming problem, the problem can be solved efficiently. Simulation results verify the performance gain implied by MIMO–CDMA relay system compared to the non-CDMA coded system.     

Short communication: Prevalence and antibiotic resistance of Staphylococcus aureus isolated from bovine clinical mastitis

The aims of this study were to determine the prevalence and antibiotic resistance of Staphylococcus aureus isolated from bovine clinical mastitis in Varamin, Tehran Province, Iran. All of the isolated Staph. aureus were identified by morphology and culture and confirmed using the API Staph identification system (bioMérieux, Marcy-l’Étoile, France). Antibiotic resistance genes were detected by PCR with oligonucleotide primers specific for each gene. Staphylococcus aureus was recovered from 43 of 207 (20.1%) bovine clinical milk samples. Using disk diffusion, methicillin-resistant Staph. aureus was detected in 5 of 43 (11.6%) samples. The pathogen showed high resistance against penicillin G (86%) and tetracycline (76.7%). The blaZ (penicillin) (86%), tetM (tetracycline), and ermC (erythromycin) genes (39.5% each) were the most prevalent antibiotic resistance genes. The findings of this study are useful for designing specific control programs for bovine clinical mastitis caused by Staph. aureus in this region of Iran.