Cost optimization of a composite floor system using an improved harmony search algorithm

In this study, cost optimization of a composite floor system is performed utilizing the harmony search algorithm and an improved harmony search algorithm. These algorithms imitate the musical performance process that takes place when a musician searches for a better state of harmony, similar to the optimum design process which looks for the optimum solution. A composite floor system is designed by the LRFD-AISC method, using a unit consisting of a reinforced concrete slab and steel beams. The objective function is considered as the cost of the structure, which is minimized subjected to serviceability and strength requirements. Examples of composite floor systems are presented to illustrate the performance of the presented algorithms.     

Measurements and modelling of free-surface turbulent flows induced by a magnetic stirrer in an unbaffled stirred tank reactor

Measurements and numerical simulations of turbulent flows with free-surface vortex in an unbaffled reactor agitated by a cylindrical magnetic stirrer are presented. Measurements of the three mean and fluctuating components of the velocity vector are made using a laser Doppler velocimetry in order to characterise the flow field at different speeds of the stirrer. A homogeneous Eulerian-Eulerian multiphase flow model coupled with a volume-of-fluid method for interface capturing is applied to determine the vortex shape and to compute the turbulent flow field in the reactor. Turbulence is modelled using a second-moment differential Reynolds-stress transport (RST) model, but for some cases the k-ε/k-ω based shear-stress transport (SST) model is also used. The predictions obtained using the ANSYS CFX-5.7 computational fluid dynamics code are compared with the images of the vortex and the measured distributions of mean axial, radial and tangential velocities and turbulent kinetic energy. The predicted general shape of the liquid free-surface is in good agreement with measurements, but the vortex depth is underpredicted. The overall agreement between the measured and the predicted axial and tangential velocities obtained with the RST model is good. However, the radial velocity is significantly underpredicted. Predictions of the turbulent kinetic energy yield reasonably good agreement with measurements in the bulk flow region, but discrepancy exists near the reactor wall where this quantity is underpredicted. The SST model predictions are generally of the same quality as those of the RST model, with the latter model providing better predictions of the tangential velocity distribution.     

Deciphering Pactamycin Biosynthesis and Engineered Production of New Pactamycin Analogues

Pactamycin is an aminocyclopentitol‐derived natural product that has potent antibacterial and antitumor activities. Sequence analysis of an 86 kb continuous region of the chromosome from Streptomyces pactum ATCC 27456 revealed a gene cluster involved in the biosynthesis of pactamycin. Gene inactivation of the Fe‐S radical SAM oxidoreductase (ptmC) and the glycosyltransferase (ptmJ), individually abrogated pactamycin biosynthesis; this confirmed the involvement of the ptm gene cluster in pactamycin biosynthesis. The polyketide synthase gene (ptmQ) was found to support 6‐methylsalicylic acid (6‐MSA) synthesis in a heterologous host, S. lividans T7. In vivo inactivation of ptmQ in S. pactum impaired pactamycin and pactamycate production but led to production of two new pactamycin analogues, de‐6‐MSA‐pactamycin and de‐6‐MSA‐pactamycate. The new compounds showed equivalent cytotoxic and antibacterial activities with the corresponding parent molecules and shed more light on the structure–activity relationship of pactamycin.     

Development and performance analysis of a data-reduction algorithmfor automotive multiplexing

Automotive multiplexing allows sharing information among various intelligent modules inside an automotive electronic system. In order to achieve an optimum functionality, the information should be exchanged among various electronic modules in real time. Data-reduction techniques are used to send the data over a transmission medium at a high speed. They can be employed in automotive multiplexing systems to improve the information exchange rate among various intelligent modules. Some off-the-shed data-reduction algorithms have been considered for automotive multiplexing. However, their applications have been limited to test data classes only. This paper introduces a data-reduction algorithm that can be applied to all data classes found in automotive multiplexing, including body- and engine-related data. Detailed performance analysis of the algorithm is presented. Although this algorithm has been developed to fit in the automotive environment, it can also be applied to nonautomotive applications in which extensive information exchange is performed among control modules via a multiplexing bus. The proposed algorithm uses SAE J1939 as a base protocol. However it can be used with other automotive multiplexing protocols without loss of generality     

Missing data analysis and homogeneity test for Turkish precipitation series

In this study, missing value analysis and homogeneity tests were conducted for 267 precipitation stations throughout Turkey. For this purpose, the monthly and annual total precipitation records at stations operated by Turkish State Meteorological Service (DMI) from 1968 to 1998 were considered. In these stations, precipitation records for each month was investigated separately and the stations with missing values for too many years were eliminated. The missing values of the stations were completed by Expectation Maximization (EM) method by using the precipitation records of the nearest gauging station. In this analysis, 38 stations were eliminated because they had missing values for more than 5 years, 161 stations had no missing values and missing precipitation values were completed in the remaining 68 stations. By this analysis, annual total precipitation data were obtained by using the monthly values. These data should be hydrologically and statistically reliable for later hydrological, meteorological, climate change modelling and forecasting studies. For this reason, Standard Normal Homogeneity Test (SNHT), (Swed-Eisenhart) Runs Test and Pettitt homogeneity tests were applied for the annual total precipitation data at 229 gauging stations from 1968 to 1998. The results of each of the testing methods were evaluated separately at a significance level of 95% and the inhomogeneous years were determined. With the application of the aforementioned methods, inhomogeneity was detected at 50 stations of which the natural structure was deteriorated and 179 stations were found to be homogeneous.     

Expressing through digital photographs: an assistive tool for persons with aphasia

This paper describes the design of an assistive tool called CoCreation that can help people with aphasia to express daily experiences by utilizing digital photographs. CoCreation can upload the user’s pictures and can cluster them as a function of the time at which the pictures were taken. Pictures taken within a short period of time are assumed to highlight a single activity. The user is able to select a cluster and can edit the pictures by dragging icons or drawing on top of them, or by typing words to create a caption. The pictures set the context for a story, while the additional tools such as keyboard and drawing pad allow the user to add information that is considered useful for sharing the experience. The paper presents the detailed design process and the preliminary evaluation of CoCreation with an experienced speech therapist.     

Effects of polypropylene twisted bundle fibers on the mechanical properties of high-strength oil palm shell lightweight concrete

In this study, the effects of a new type of non-metallic fiber (polypropylene twisted bundle (PPTB)) on the slump and mechanical properties of oil palm shell (OPS) concrete have been investigated. The results showed that increasing the volume fraction of PPTB fibers, it slightly decreases the workability and density of the concrete. It has found that the compressive strength of OPS concrete increases with increasing PPTB fiber volume fraction. The results revealed that the reinforcement of OPS concrete with steel and PPTB fibers reduces the strength loss of OPS concrete in poor curing environments. In addition, the fiber with low volume fraction (up to 0.25 %) is more efficient in improving the flexural strength of OPS concrete compared to its splitting tensile strength. The average modulus of elasticity (E value) is obtained to be 17.4 GPa for all mixes, which is higher than the values reported in previous studies and is within the range for normal weight concrete. The performance of the PPTB fibers is comparable to that for steel fibers at a volume fraction (V_f) of 0.5 %, which provides less dead load for lightweight concrete. The findings of this study showed that the PPTB fibers can be used as an alternative material to enhance the properties of OPS concrete. Hence, PPTB fibers are a promising alternative for lightweight concrete applications.     

Form one students’ engagement with computer games and its effect on their academic achievement in a Malaysian secondary school

The main purpose of the study was to address the association between computer games and students’ academic achievement. The exceptional growth in numbers of children playing computer games, the uneasiness and incomplete understanding foundation when starting the discussion on computer games have stimulated this study to be conducted. From a survey conducted on 236 form one students in one of the Malaysian secondary school, 75.8 percent were gamers. Playing computer games seemed to be more stereotypically boy’s activity with 91.3 percent of the boys engaged in computer games compared to 54.1 percent among the girls. They spent an average of 8.47 hours per week playing computer games. Parents and teachers’ concern about computer games was not something that went unwarranted as an overall result was predicting computer games as having negative associations with students’ academic achievement. However, in-depth analyses by combinations of classes done step by step indicated that the initial results could be overruled by students from the last class, whom need extra attentions. As a conclusion, the findings in this study suggest some interesting yet ultimately weak associations between playing computer games and students’ academic achievement. Nevertheless, caution is warranted in making any generalization as looking at the population as a whole will be different from its components. The generalizability of this study’s findings is limited by the nature of the sample. Even so, blaming computer games for the students’ bad academic performance in school is unjustified as there are many more other factors to look into before finding computer games as the scapegoat.     

Optofluidics: a novel generation of reconfigurable and adaptive compact architectures

The integration of microfluidics and microphotonics brings the ability to tune and reconfigure ultra-compact optical devices. This flexibility is essentially provided by three characteristics of fluids that are scalable at the micron-scale: fluid mobility, large ranges of index modulation, and abrupt interfaces that can be easily reshaped. Several examples of optofluidic devices are presented here to illustrate the achievement of flexible devices on (semi) planar and compact platforms. First, we report an integrated geometry for a compact and tunable interferometer that exploits a sharp and mobile air/water interface. We then describe a class of optically controlled devices that rely on the actuation of optically trapped micron-sized objects within a fluid environment. The last architecture results from the infiltration of photonic crystal devices with fluids. This produces tunable and reconfigurable photonic devices, like optical switches. Higher degrees of functionality could be achieved with sophisticated optofluidic platforms that associate complex microfluidic delivery and mixing schemes with microphotonic devices. Moreover, optofluidics offers new opportunities for realizing highly responsive and compact sensors.