Investigation of Dynamic and Static Recrystallization Behavior During Thermomechanical Processing in a API-X70 Microalloyed Steel

Recovery and recrystallization phenomena and effects of microalloying elements on these phenomena are of great importance in designing thermomechanical processes of microalloyed steels. Control of these phenomena can lead to manufacturing of products with suitable structures and desirable properties. The aim of this study was to investigate the microstructural evolution occurring during thermomechanical processing through hot compression testing. The niobium carbonitride approximate solution temperature was initially determined to guess the optimum reheating temperature. Then continuous and interrupted compression tests were utilized to physically model the dynamic and static recrystallization (SRX) behavior of the steel during thermomechanical processing. The parameters of the flow stress model and the activation energy of dynamic recrystallization (DRX) were calculated and the effects of deformation conditions on peak strain of DRX were evaluated. In addition, a kinetic study of the static softening of austenite indicated that the plateau occurred in recrystallization fraction-time curves below 1025 °C. This was considered in determining the Static Recrystallization Critical Temperature (SRCT) and construction of the Recrystallization Retardation-Temperature Time (RRTT) diagram for this steel.     

Sex and age distribution in transport-related injuries in Tehran

Intercountry or regional differences in patterns of injury by the road user type have significant implication for prevention policies. In order to have an estimate from the existing conditions of transport-related injuries (TRIs) and especially to evaluate sex and age distribution of traffic accident victims, we analyzed information of 8426 hospitalized trauma patients during 13 months of data gathering process. Forty-five percent of the injuries were related to car accidents and men/women ratio in these patients was 4.2/1. The highest men/women ratio was (16/1) for motorcyclists, while the lowest ratio (1/1), was for rear seat car passengers. Mean (+/-S.D.) age of the patients was 31 (+/-18), and men were nearly 2 years younger than women (33 versus 31). Sixty-seven percent of the females' and 44% of the males' injuries were related to pedestrian crashes. Motorcycle-related injuries in men and car passenger related injuries in women were the second most common type of crash (42 and 22%, respectively). The use of protective devices in our population was worrisome. In only 6% of the male motorcyclists helmet use was reported, and 3% of the male car occupants had used seatbelts at the time of the accident. The condition in the female population was much worse and no use of the protective devices was reported in this group of the patients. Crude mortality rate in men was nearly two times that of women (6.2% versus 3.8%). After adjustment for age, injury severity score (ISS) and category of the road users, men and women had similar mortality rate.     

Resource provisioning based on preempting virtual machines in distributed systems

Resource provisioning is one of the main challenges in large‐scale distributed systems such as federated Grids. Recently, many resource management systems in these environments have started to use the lease abstraction and virtual machines (VMs) for resource provisioning. In the large‐scale distributed systems, resource providers serve requests from external users along with their own local users. The problem arises when there is not sufficient resources for local users, who have higher priority than external ones, and need resources urgently. This problem could be solved by preempting VM‐based leases from external users and allocating them to the local ones. However, preempting VM‐based leases entails side effects in terms of overhead time as well as increasing makespan of external requests. In this paper, we model the overhead of preempting VMs. Then, to reduce the impact of these side effects, we propose and compare several policies that determine the proper set of lease(s) for preemption. We evaluate the proposed policies through simulation as well as real experimentation in the context of InterGrid under different working conditions. Evaluation results demonstrate that the proposed preemption policies serve up to 72% more local requests without increasing the rejection ratio of external requests. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of conjugated linoleic acid, fish oil and soybean oil on PPARs (α & γ) mRNA expression in broiler chickens and their relation to body fat deposits

An experiment was conducted on broiler chickens to study the effects of different dietary fats (Conjugated linoleic acid (CLA), fish oil, soybean oil, or their mixtures, as well as palm oil, as a more saturated fat), with a as fed dose of 7% for single fat and 3.5 + 3.5% for the mixtures, on Peroxisome Proliferator-Activated Receptors (PPARs) gene expression and its relation with body fat deposits. The CLA used in this experiment was CLA LUTA60 which contained 60% CLA, so 7% and 3.5% dietary inclusions of CLA LUTA60 were equal to 4.2% and 2.1% CLA, respectively. Higher abdominal fat pad was found in broiler chickens fed with a diet containing palm oil compared to chickens in the other experimental groups (P ≤ 0.05). The diets containing CLA resulted in an increased fat deposition in the liver of broiler chickens (P ≤ 0.05). The only exception was related to the birds fed with diets containing palm oil or fish oil + soybean oil, where contents of liver fat were compared to the CLA + fish oil treatment. PPARγ gene in adipose tissue of chickens fed with palm oil diet was up-regulated compared to other treatments (P ≤ 0.001), whereas no significant differences were found in adipose PPARγ gene expression between chickens fed with diets containing CLA, fish oil, soybean oil or the mixture of these fats. On the other hand, the PPARα gene expression in liver tissue was up-regulated in response to the dietary fish oil inclusion and the differences were also significant for both fish oil and CLA + fish oil diets compared to the diets with palm oil, soybean oil or CLA as the only oil source (P ≤ 0.001). In conclusion, the results of present study showed that there was a relationship between the adipose PPARγ gene up-regulation and abdominal fat pad deposition for birds fed with palm oil diet, while no deference was detected in n-3 and n-6 fatty acids, as well as CLA on PPARγ down regulation in comparison to a more saturated fat. When used on its own, fish oil was found to be a more effective fat in up-regulating hepatic PPARα gene expression and this effect was related to a less fat deposition in liver tissue. A negative correlation coefficient (-0.3) between PPARα relative gene expression and liver tissue fat content confirm the anti-lipogenic effect of PPARα, however, the change in these parameters was not completely parallel.     

A new empirical viscosity model for ceramic suspensions

This paper presents a new predictive viscosity model for ceramic suspensions. Starting from Einstein's model (1906), various theoretical, empirical, and phenomenological models have been proposed for different suspension systems. However, there is still a lack of reliable model for ceramic suspensions used in colloidal ceramic shape-forming methods. Here, the rheological properties of ceramic suspensions comprising NiO/YSZ (nickel oxide/yttria stabilized zirconia) as the ceramic powder, and furfuryl alcohol as the suspending media were measured over a range of shear-rates (between 1 and 1000 s⁻¹) and different solid volume fractions from 0 to 0.4010. An empirical equation was then developed for the ceramic suspensions using the mobility parameter (?/(?_m−?)), which links Einstein's model with the more recent relative viscosity models. The proposed model was used to predict the relative viscosity data, showing excellent agreement to the experimental data from this study and with reported data in literature for other ceramic systems. The model was also used to estimate the maximum solid volume fraction for the ceramic suspensions (?_m=0.571), with better accuracy than those estimated by existing models.     

A two-phase genetic K-means algorithm for placement of radioports in cellular networks.

This paper proposes a two-phase hybrid algorithm for optimal placement of radioports. The placement strategy minimizes the dynamic range of the channel, and thus reduces the peak transmit power needed by a wireless handset. The performance of the proposed algorithm is compared with that of an exhaustive search, as well as with that of a simplex algorithm. Simulation results show that the two-phase hybrid algorithm, although suboptimal, outperforms the simplex algorithm with only a modest increase in computation time. It has the added advantage of being quite insensitive to the seed solution.     

Modeling and scheduling open shops with sequence-dependent setup times to minimize total completion time

It is known that in many real industrial settings, some setup is carried out before the process of a job. Usually, the magnitude of this setup depends on the order of two consecutive jobs. In this case, the setup is called sequence-dependent. This paper deals with open shop scheduling with sequence-dependent setup times to minimize the total completion time. The problem is formulated as an effective mixed integer linear programming model that best characterizes and solves to optimality small-sized instances of the problem under consideration. Since the electromagnetism-like metaheuristic (EM) is successfully applied to some NP-hard problems, we have been motivated to employ and assess the effectiveness of EM to solve the open shop with setup times. To further enhance EM, a local search engine in form of a fast and simple simulated annealing is incorporated. In order to evaluate the performance of the proposed algorithms, an experiment is designed where the proposed methods are compared against some algorithms in the literature. The related results are analyzed by statistical tools. The experimental results and statistical analyses demonstrate that the proposed model and EM are effective for the problem.     

Spectrum sensing and power/rate control in CDMA cognitive radio networks

In this paper, a two‐phase algorithm for the spectrum sensing and power/rate control of a secondary user (S‐user) or cognitive radio is proposed. In the first phase, the primary base station (P‐BS), which is conscious of both the number and the data rate of primary active users (P‐user), broadcasts theitusage capacity percentage (UCP) of its cell. Since knowing only the UCP is not enough to guarantee that the total load (of P‐users and S‐users) is less than a maximum permissible load, the S‐user must measure the total interference received from both the P‐users and other S‐users. In this direction, using both the UCP and measurement of the interference received from the P‐users and the S‐users by the S‐user or secondary base station (S‐BS), we mathematically derive an equation for issuing data transmission permission, which if it is held then the second phase of the algorithm: the transmit power/rate control starts. In this phase, the S‐user and the S‐BS look for feasible values for the transmit power level and transmission rate. If there are feasible values, it starts its transmission at these feasible transmit power and rate. Since both the location of the S‐user and the channel condition vary in time, the whole algorithm is iterated periodically with a period faster than the coherence time of the channel. Furthermore, we consider the down link of the above system with cooperation among neighboring S‐users to overcome fading channels and we investigate the amount of improvement in the reliability of the issuing data transmission permission. As well, we consider the uplink of the system with multiple antennas in the S‐BS to investigate the improvement in the same parameter over spatially correlated and independent fading channels. Theoretical analysis is validated using computer simulations. Both theoretical analysis and computer simulations show that the proposed cooperative spectrum sensing algorithm performs properly at SNR = ?5dB in flat Nakagami‐m fading channels with m = 1 even in correlated fading channels. We also address the improvement of the reliability of the issuing data transmission permission in the uplink in case of using multiple antennas only in the S‐BS. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of α-amylase inhibitory activities of selected antidiabetic medicinal plants

Inhibitors of carbohydrate hydrolyzing enzymes such as α-amylase play an important role for the control of diabetes mellitus especially in patients with type 2 diabetes. In this study we selected ten antidiabetic medicinal plants, because they have been recommended to treat diabetes in traditional Iranian medicine, and screened them for α-amylase inhibitory activities. Among the tested samples, Camellia sinensis (Theaceae) leaf (IC₅₀ = 1.54 mg/mL), Trigonella foenum-graecum (Leguminosae) seed (IC₅₀ = 1.87 mg/mL) and leaf (IC₅₀ = 1.92 mg/mL), and Urtica dioica (Urticaceae) leaf (IC₅₀ = 1.89 mg/mL) revealed appreciable α-amylase inhibitory activities in a concentration-dependent manner. Furthermore, the most active sample, Camellia sinensis leaf, was partitioned by stepwise solvent–solvent extraction process and the inhibitory effect of each fraction on the α-amylase was tested. According to the results, the ethyl acetate fraction (IC₅₀ = 0.53 mg/mL) and the residue (IC₅₀ = 0.52 mg/mL) had the highest α-amylase inhibitory activities.