Electro-copolymerisation of indene and styrene

Electroinitiated cationic copolymerisation of indene and styrene was investigated by constant potential electrolysis. Effects of copolymerisation potential and temperature on the copolymer composition and the reactivity ratios are discussed. The reactivity ratios of the monomers were calculated according to the integrated Lewis-Mayo equation.     

Study of liquid injection impact on the performance of new refrigerant mixtures

In this paper, the test results of liquid injection impact on the performance of new alternative refrigerant mixtures such as: R-410A, R-507, R-407C and R-404A are discussed, analysed and presented. The test results were obtained using an air-source heat pump set-up with enhanced surface tubing under various liquid injection ratios. Performance tests were conducted according to the ARI/ASHRAE standards. The performance data demonstrated that as liquid injection ratio increases, compressor head pressure and discharge temperature decrease. This has a positive effect in protecting the compressor. The effect of liquid injection on mixture behaviour varies from one mixture to another depending upon the mixture's composition. Furthermore, liquid injection appears to have a significant influence on R-410A behaviour compared to the other mixtures in question. Copyright © 2002 John Wiley & Sons, Ltd.     

In vitro cytotoxicity and DNA damage production in Chinese hamster ovary cells and topoisomerase II inhibition by 2-[2''-(dimethylamino)ethyl]-1, 2-dihydro-3H-dibenz[de,h]isoquinoline-1,3-diones with substitutions at the 6 and 7 positions (azonafides)

The p53 tumor suppressor gene encodes a phosphoprotein which when overexpressed can induce growth arrest at the G1 and G2/M phases of the cell cycle, promote differentiation and apoptosis. This paper demonstrates that p53 can associate with trk tyrosine kinase. Expression of a murine temperature-sensitive (ts) p53 mutant in PC12 cells overexpressing trk (a model system to analyse cellular differentiation and signal transduction induced by NGF) induces morphological changes in the absence of NGF stimulation at 32 degrees C but not at 37 degrees C. In cells differentiated by p53, trk, but not EGFr, was hyperphosphorylated on tyrosine. Furthermore trk was not phosphorylated when expressed in Saos-2 cells (human osteosarcoma cells that lack expression of both endogenous trk and p53) at either temperature. However, transfection of ts p53 into these cells induces trk phosphorylation at 32 degrees C in the absence of NGF stimulation. Association of trk and p53 can be detected in NIH3T3 and PC12 cells co-expressing trk and the ts p53 mutant, in NIH3T3 and PC12 cells transfected with trk alone, and in untransfected PC12 cells, showing that overexpressed and/or endogenous trk associates with endogenous, low levels of p53. These data suggest a novel function for p53 which involves the stimulation of signal transduction pathways (mediating morphological properties of cells), possibly through association with and hyperphosphorylation of trk.     

Automatic design of marine structures by using successive response surface method

An automated optimization procedure based on successive response surface method is presented. The method is applied to weight optimization of a stiffened plate used in marine structures. In the design space the surrogate model is spanned sequentially into an optimally restricted subspace that is converging towards at least a local optimum. Both objective function and all constraint functions are modeled using linear response surface method enabling the use of a robust and efficient simplex algorithm for the optimizations. Special attention is paid to CAD and FEM-model linking that plays a central role in practical industrial applications. In this project SOLIDWORKS and ANSYS software are adopted for structural modeling and analysis, respectively, and the optimization is carried out in a MatLab environment. The reported results achieved in this project prove the robustness and effectiveness of the proposed approach.     

Medium chain triglyceride in early life: Effects on growth of adipose tissue

Effects of feeding early in life a diet high in either long chain (LCT) or medium chain triglyceride (MCT) were studied on the development of adipose tissue in post-weanling rats. The diets were similar in calorie distribution and identical in nutrients except for type of fat. The caloric distribution of the two diets by percent was LCT (corn oil)/protein/carbohydrate, 70/18/12 and MCT/corn oil/protein/carbohydrate, 66/4/18/12. Male littermates with less than 5% weight difference were pair-fed the two diets randomly at age 18–20 days. One-fourth of the rats were killed at 10, 16, 22 and 28 weeks of age and analyzed for adipose depots and adipose tissue cellularity. Results showed that the LCT-fed rats were significantly heavier, with larger epididymal, retroperitoneal, omental and subcutaneous fat pads than the respective pair-fed MCT rats. Also, LCT-fed rats had larger size and number of adipocytes than MCT-fed littermates. It is concluded that the type of fat in the diet, namely LCT or MCT, when fed early in life can influence the development of adipose tissue. MCT appears less lipogenic than LCT. The mechanism for the diminished adiposity of MCT-fed rats is related to extensive oxidation of MCT and its enhancement of thermogenesis leading to lessened energy efficiency. Presented at the symposium on “Specialty Lipids and Their Biofunctionality” at the annual meeting of the American Oil Chemists' Society, Philadelphia, May 1985.     

A reverse osmosis desalting plant operated by gas turbines

Power plants in Kuwait use gas turbines (GT) only for a few hours to produce power at peak load times. Peak loadoccurs in the summer due to the air-conditioning load. As an example, the average number of operating hours for six gas turbines in the Doha East power plant was 16 in the summer of 2001. There is little concern about efficiency of these GT since they work for a very short time during the year. However, a recent increase in desalted seawater demand suggests the use of these GT to operate reverse osmosis (RO) desalting systems all year around. The summer outside design temperature in Kuwait for air-conditioning calculations is 48°C dry bulb temperature (DBT), and 28°C wet bulb temperature (WBT); but the ambient temperature can easily reach 60°C. Gas turbine power output and efficiency are drastically reduced by the increase in temperature of intake air to the gas turbine's compressor, especially during harsh Kuwaiti summer conditions. Thus, it is essential to investigate cooling of air intake to the GT compressor. The performance of a typical GT unit and its ability to produce desalted waterby a RO desalting system at different ambient temperatures are presented. Calculation of needed capacities for the cooling of intake air to the GT compressor was performed for evaporative cooling, single and multiple mechanical vapor compression cycles, and combined indirect evaporation cooling with the refrigeration system. The improvements of power output and efficiency due to the cooling of air intake of the GT and the resulting increase in desalted water are also presented.     

A novel secure solution of using mixed reality in data transmission for bowel and jaw surgical telepresence: enhanced rivest cipher RC6 block cipher

Security threats are crucial challenges that deter Mixed reality (MR) communication in medical telepresence. This research aims to improve the security by reducing the chances of types of various attacks occurring during the real-time data transmission in surgical telepresence as well as reduce the time of the cryptographic algorithm and keep the quality of the media used. The proposed model consists of an enhanced RC6 algorithm in combination. Dynamic keys are generated from the RC6 algorithm mixed with RC4 to create dynamic S-box and permutation table, preventing various known attacks during the real-time data transmission. For every next session, a new key is created, avoiding possible reuse of the same key from the attacker. The results obtained from our proposed system are showing better performance compared to the state of art. The resistance to the tested attacks is measured throughout the entropy, Pick to Signal Noise Ratio (PSNR) is decreased for the encrypted image than the state of art, structural similarity index (SSIM) closer to zero. The execution time of the algorithm is decreased for an average of 20%. The proposed system is focusing on preventing the brute force attack occurred during the surgical telepresence data transmission. The paper proposes a framework that enhances the security related to data transmission during surgeries with acceptable performance.

     

Studying the needed effort for identifying duplicate issues

Many recent software engineering papers have examined duplicate issue reports. Thus far, duplicate reports have been considered a hindrance to developers and a drain on their resources. As a result, prior research in this area focuses on proposing automated approaches to accurately identify duplicate reports. However, there exists no studies that attempt to quantify the actual effort that is spent on identifying duplicate issue reports. In this paper, we empirically examine the effort that is needed for manually identifying duplicate reports in four open source projects, i.e., Firefox, SeaMonkey, Bugzilla and Eclipse-Platform. Our results show that: (i) More than 50 % of the duplicate reports are identified within half a day. Most of the duplicate reports are identified without any discussion and with the involvement of very few people; (ii) A classification model built using a set of factors that are extracted from duplicate issue reports classifies duplicates according to the effort that is needed to identify them with a precision of 0.60 to 0.77, a recall of 0.23 to 0.96, and an ROC area of 0.68 to 0.80; and (iii) Factors that capture the developer awareness of the duplicate issue’s peers (i.e., other duplicates of that issue) and textual similarity of a new report to prior reports are the most influential factors in our models. Our findings highlight the need for effort-aware evaluation of approaches that identify duplicate issue reports, since the identification of a considerable amount of duplicate reports (over 50 %) appear to be a relatively trivial task for developers. To better assist developers, research on identifying duplicate issue reports should put greater emphasis on assisting developers in identifying effort-consuming duplicate issues.     

Active fault tolerant control for nonlinear systems with simultaneous actuator and sensor faults

The goal of this paper is to describe a novel fault tolerant tracking control (FTTC) strategy based on robust fault estimation and compensation of simultaneous actuator and sensor faults. Within the framework of fault tolerant control (FTC) the challenge is to develop an FTTC design strategy for nonlinear systems to tolerate simultaneous actuator and sensor faults that have bounded first time derivatives. The main contribution of this paper is the proposal of a new architecture based on a combination of actuator and sensor Takagi-Sugeno (T-S) proportional state estimators augmented with proportional and integral feedback (PPI) fault estimators together with a T-S dynamic output feedback control (TSDOFC) capable of time-varying reference tracking. Within this architecture the design freedom for each of the T-S estimators and the control system are available separately with an important consequence on robust L ₂ norm fault estimation and robust L ₂ norm closed-loop tracking performance. The FTTC strategy is illustrated using a nonlinear inverted pendulum example with time-varying tracking of a moving linear position reference.