Search results for: Dwell time effect

Authors: Dessie Fisseha, Derbew Belew, Ambecha Olika

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Potato is a high-potential food security crop in Ethiopia. However, the yield and productivity of the crop have been far below the world average. This is due to several factors, including appropriate agronomic practices, such as time of earthing-up and inflorescence management. A field experiment was conducted at Jimma, Southwest Ethiopia, during 2016/17 under irrigation to determine the effect of time of earthing-up and inflorescence removal on the growth, yield, and quality of potatoes. The treatments consisted of a time of earthing-up (no earthing-up, earthing-up at 15, 30, and 45 days after complete plant emergence) and inflorescence removal (inflorescence removed and not removed). Potato variety (Belete) was used for this experiment. A 2x4 factorial experiment was laid out with three replications. Data collected on the growth, yield, and quality components of potatoes were analyzed using SAS Version 9.3 statistical software. Inflorescence removal affected the majority of the growth and yield parameters, while the time of earthing-up affected all growth, yield, and quality (green tuber number) parameters. Earthing-up at 15 days in combination with inflorescence removal (at 60 days after complete plant emergence) gave better plant growth and maximum tuber yield of the Belete potato variety under irrigated conditions. Since the current research was conducted at one location, in one season, and with one potato cultivar (Belete), it would be advisable to repeat the experiment so as to arrive at a final conclusion and subsequent recommendation.

Keywords: Belete, earthing-up, inflorescence, yield

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Authors: Hasan Ziari, Hassan Fazaeli, Seyed Javad Vaziri Kang Olyaei, Asma Sadat Dabiri

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The presence of cracks in concrete pavements is a place for the ingression of corrosive substances, acids, oils, and water into the pavement and reduces its long-term durability and level of service. One of the causes of early cracks in concrete pavements is the plastic shrinkage. This shrinkage occurs due to the formation of negative capillary pressures after the equilibrium of the bleeding and evaporation rates at the pavement surface. These cracks form if the tensile stresses caused by the restrained shrinkage exceed the tensile strength of the concrete. Different climate conditions change the rate of evaporation and thus change the balance time of the bleeding and evaporation, which changes the severity of cracking in concrete. The present study examined the relationship between the balance time of bleeding and evaporation and the area of cracking in the concrete slabs using the standard method ASTM C1579 in 27 different environmental conditions by using continuous video recording and digital image analyzing. The results showed that as the evaporation rate increased and the balance time decreased, the crack severity significantly increased so that by reducing the balance time from the maximum value to its minimum value, the cracking area increased more than four times. It was also observed that the cracking area- balance time curve could be interpreted in three sections. An examination of these three parts showed that the combination of climate conditions has a significant effect on increasing or decreasing these two variables. The criticality of a single factor cannot cause the critical conditions of plastic cracking. By combining two mild environmental factors with a severe climate factor (in terms of surface evaporation rate), a considerable reduction in balance time and a sharp increase in cracking severity can be prevented. The results of this study showed that balance time could be an essential factor in controlling and predicting plastic shrinkage cracking in concrete pavements. It is necessary to control this factor in the case of constructing concrete pavements in different climate conditions.

Keywords: bleeding and cracking severity, concrete pavements, climate conditions, plastic shrinkage

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Authors: Anita Vidacs, Robert Rajko, Csaba Vagvolgyi, Judit Krisch

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With the optimization of a new disinfectant the number of tests could be decreased and the cost of processing too. Good sanitizers are eco-friendly and allow no resistance evolvement of bacteria. The essential oils (EOs) are natural antimicrobials, and most of them have the Generally Recognized As Safe (GRAS) status. In our study, the effect of the EOs cinnamon, marjoram, and thyme was investigated against mixed species bacterial biofilms of Escherichia coli, Listeria monocytogenes, Pseudomonas putida, and Staphylococcus aureus. The optimal concentration of EOs, disinfection time and level of pH were evaluated with the aid of Response Surface Box-Behnken Design (RSD) on 1 day and 7 days old biofilms on metal, plastic, and wood surfaces. The variable factors were in the range of 1-3 times of minimum bactericide concentration (MBC); 10-110 minutes acting time and 4.5- 7.5 pH. The optimized EO disinfectant was compared to industrial used chemicals (HC-DPE, Hypo). The natural based disinfectants were applicable; the acting time was below 30 minutes. EOs were able to eliminate the biofilm from the used surfaces except from wood. The disinfection effect of the EO based natural solutions was in most cases equivalent or better compared to chemical sanitizers used in food industry.

Keywords: biofilm, Box-Behnken design, disinfectant, essential oil

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Authors: N. Benabdeslam, N. Bouzidi, F. Atmani, R. Boucif, A. Sakhri

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The objective of this study was to provide answers for a better understanding of the mechanisms involved during grinding. To obtain a phosphate powder, we carry out sieving - grinding circuits for each parameter influencing the process. The analysis of the average particle size of the different tests carried out served in the first place as a basis for the determination of the granulometric curve area, the characteristics and the granular coefficients, then the exploitation of the different results for the calculation of the energies consumed for the fragmentation of different ore types, the energy coefficients as well as the ability to grind. Indeed, a time of 5 to 10 minutes can be chosen as the optimal grinding time in a disc mill for a % in weight of the highest pass. However, grinding time can influence the granular characteristics of ore.

Keywords: characteristic granular, grinding, mineralogical composition, phosphate ore, parameters

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Authors: Zakaria Aketouane, Mustapha Malha, Abdellah Bah, Omar Ansari, Mohamed Asbik

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The present paper deals with the thermal performance of a hollow-brick filled with Phase Change Material (PCM). The main objective is to study the effect of percentage and melting temperature of the PCM on the thermal inertia and internal surface temperature of the hollow-brick. A numerical model based on the heat transfer equation and the apparent heat capacity method has been validated using experimental study from the literature. The results show that increasing the percentage of the PCM has a significant effect on time lag and decrement factor that define the thermal inertia; the internal temperature is reduced by 1.36°C to 5.39°C for a percentage from 11% to 71% in comparison to a brick without PCM. In addition, an appropriate melting temperature of 37°C has been deduced for the horizontal wall orientation in Rabat in comparison to 27°C and 47°C.

Keywords: appropriate melting temperature, decrement factor, phase change material, thermal inertia, time lag

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Authors: Khurram Shahzad, Muhammad Usman

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The main aim of this study is to examine the direct and interactive effects of job insecurity and Islamic work ethics on employee’s attitude towards change and organizational citizenship behavior. Design/methodology/approach: The data was collected from 171 male and female university teachers of Pakistan. Self administered, close ended questionnaires were used to collect the data. Data was analyzed through correlation and regression analysis. Findings: Through the analysis of data, it was found that job insecurity has a strong negative effect on the attitude towards change of university teachers. On the contrary, job insecurity has no significant effect on organizational citizenship behavior of university teachers. Our results also show that Islamic work ethics does not moderate the relationship of job insecurity and attitude towards change, while a strong moderation effect of Islamic wok ethics is found on the relationship of job insecurity and organizational citizenship behavior. Originality/value: This study for the first time examines the relationship of job insecurity with employee’s attitude towards change and organizational citizenship behavior with the moderating effect of Islamic work ethics.

Keywords: job security, islamic work ethics, attitude towards change, organizational citizenship behavior

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Authors: A. Guerrero, A. Leon, S. Munoz, M. Sandoval

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The addition of solvent to cyclic steam stimulation is done in order to reduce the solvent-vapor ratio at late stages of the process, the moment in which this relationship increases significantly. The study of the use of naphtha in addition to the cyclic steam stimulation has been mainly oriented to the effect it achieves on the incremental recovery compared to the application of steam only. However, the effect of naphtha on the reactivity of crude oil components under conditions of cyclic steam stimulation or if its effect is the only dilution has not yet been considered, to author’s best knowledge. The present study aims to evaluate and understand the effect of naphtha and the conditions of cyclic steam stimulation, on the remaining composition of the improved oil, as well as the main mechanisms present in the heavy crude - naphtha interaction. Tests were carried out with the system solvent (naphtha)-oil (12.5° API, 4216 cP @ 40° C)- steam, in a batch micro-reactor, under conditions of cyclic steam stimulation (250-300 °C, 400 psi). The characterization of the samples obtained was carried out by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) and NMR (Nuclear Magnetic Resonance) techniques. The results indicate that there is a rearrangement of the microstructure of asphaltenes, resulting in a decrease in these and an increase in lighter components such as resins.

Keywords: composition change, cyclic steam stimulation, interaction mechanism, naphtha

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Authors: Jesika A. Walker, Mohammed Aswad, Guy Lacroix, Denis Cousineau

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There is a fundamental disconnect between the experience of time passing and the chronometric units by which time is quantified. Specifically, there appears to be no relationship between the passage of time judgments (PoTJs) and verbal duration estimates at short durations (e.g., < 2000 milliseconds). When a duration is longer than several minutes, however, evidence suggests that a slower feeling of time passing is predictive of overestimation. Might the length of a task moderate the relation between PoTJs and duration estimates? Similarly, the estimation paradigm (prospective vs. retrospective) and the mental effort demanded of a task (task demand) have both been found to influence duration estimates. However, only a handful of experiments have investigated these effects for tasks of long durations, and the results have been mixed. Thus, might the length of a task also moderate the effects of the estimation paradigm and task demand on duration estimates? To investigate these questions, 273 participants performed either an easy or difficult visual and memory search task for either eight or 58 minutes, under prospective or retrospective instructions. Afterward, participants provided a duration estimate in minutes, followed by a PoTJ on a Likert scale (1 = very slow, 7 = very fast). A 2 (prospective vs. retrospective) × 2 (eight minutes vs. 58 minutes) × 2 (high vs. low difficulty) between-subjects ANOVA revealed a two-way interaction between task demand and task duration on PoTJs, p = .02. Specifically, time felt faster in the more challenging task, but only in the eight-minute condition, p < .01. Duration estimates were transformed into RATIOs (estimate/actual duration) to standardize estimates across durations. An ANOVA revealed a two-way interaction between estimation paradigm and task duration, p = .03. Specifically, participants overestimated the task more if they were given prospective instructions, but only in the eight-minute task. Surprisingly, there was no effect of task difficulty on duration estimates. Thus, the demands of a task may influence ‘feeling of time’ and ‘estimation time’ differently, contributing to the existing theory that these two forms of time judgement rely on separate underlying cognitive mechanisms. Finally, a significant main effect of task duration was found for both PoTJs and duration estimates (ps < .001). Participants underestimated the 58-minute task (m = 42.5 minutes) and overestimated the eight-minute task (m = 10.7 minutes). Yet, they reported the 58-minute task as passing significantly slower on a Likert scale (m = 2.5) compared to the eight-minute task (m = 4.1). In fact, a significant correlation was found between PoTJ and duration estimation (r = .27, p <.001). This experiment thus provides evidence for a compensatory effect at longer durations, in which people underestimate a ‘slow feeling condition and overestimate a ‘fast feeling condition. The results are discussed in relation to heuristics that might alter the relationship between these two variables when conditions range from several minutes up to almost an hour.

Keywords: duration estimates, long durations, passage of time judgements, task demands

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Authors: Eva Tvrdá, Boris Botman, Marek Halenár, Tomáš Slanina, Norbert Lukáč

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In vitro storage and processing of animal semen represents a risk factor to spermatozoa vitality, potentially leading to reduced fertility. A variety of substances isolated from natural sources may exhibit protective or antioxidant properties on the spermatozoon, thus extending the lifespan of stored ejaculates. This study compared the ability of different concentrations of the Salvia officinalis extract on the motility, mitochondrial activity, viability and reactive oxygen species (ROS) production by bovine spermatozoa during different time periods (0, 2, 6 and 24 h) of in vitro culture. Spermatozoa motility was assessed using the Computer-assisted sperm analysis (CASA) system. Cell viability was examined using the metabolic activity MTT assay, the eosin-nigrosin staining technique was used to evaluate the sperm viability and ROS generation was quantified using luminometry. The CASA analysis revealed that the motility in the experimental groups supplemented with 0.5-2 µg/mL Salvia extract was significantly lower in comparison with the control (P<0.05; Time 24 h). At the same time, a long-term exposure of spermatozoa to concentrations ranging between 0.05 µg/mL and 2 µg/mL had a negative impact on the mitochondrial metabolism (P<0.05; Time 24 h). The viability staining revealed that 0.001-1 µg/mL Salvia extract had no effects on bovine male gametes, however 2 µg/mL Salvia had a persisting negative effect on spermatozoa (P<0.05). Furthermore 0.05-2 µg/mL Salvia exhibited an immediate ROS-promoting effect on the sperm culture (P>0.05; Time 0 h and 2 h), which remained significant throughout the entire in vitro culture (P<0.05; Time 24 h). Our results point out to the necessity to examine specific effects the biomolecules present in Salvia officinalis may have individually or collectively on the in vitro sperm vitality and oxidative profile.

Keywords: bulls, CASA, MTT test, reactive oxygen species, sage, Salvia officinalis, spermatozoa

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Authors: Dewi Tristantini, Jason Jonathan

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Coronary Artery Disease (CAD) is one of the deathliest diseases which is caused by atherosclerosis. Atherosclerosis is a disease that plaque builds up inside the arteries. Plaque is made up of fat, cholesterol, calcium, platelet, and other substances found in blood. The current treatment of atherosclerosis is to provide antiplatelet therapy treatment, but such treatments often cause gastrointestinal irritation, muscle pain and hormonal imbalance. Mimusops elengi L.’s leaves can be utilized as a natural and cheap antiplatelet’s source because it contains flavonoids such as quertecin. Antiplatelet aggregation effect of Mimusops elengi L.’s leaves’ wet extract was measured by bleeding time on DDY strain mice with the test substances were given orally during the period of 8 days. The bleeding time was measured on first day and 9th day. Empirically, the dose which is used for humans is 8.5 g of leaves in 600 ml of water. This dose is equivalent to 2.1 g of leaves in 350 ml of water for mice. The extract was divided into 3 doses for mice: 0.05 ml/day; 0.1 ml/day; 0.2 ml/day. After getting the percentage of the increase in bleeding time, data were analyzed by analysis of variance test (Anova), followed by individual comparison within the groups by LSD test. The test substances above respectively increased bleeding time 21%, 62%, and 128%. As the conclusion, the 0.02 ml/day dose of Mimusops elengi L.’s leaves’ wet extract could increase bleeding time better than clopidogrel as positive controls with 110% increase in bleeding time.

Keywords: antiplatelets, atheroschlerosis, bleeding time, Mimusops elengi

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Authors: Khalid Ahmed Elrabie Abdelrasoul

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The present study was carried out on Sahiwal cattle bulls maintained at the Artificial Breeding Complex, NDRI, Karnal, Hayana, India, to assess the effect of cooling using mist cooling and fanning on Sahiwal bulls in the dry hot summer season. Fourteen Sahiwal bulls were divided into two groups of seven each. Sexual behavior and semen quality traits considered were: Reaction time (RT), Dismounting time (DMT), Total time taken in mounts (TTTM), Flehmen response (FR), Erection Score (ES), Protrusion Score (PS), Intensity of thrust (ITS), Temperament Score (TS), Libido Score (LS), Semen volume, Physical appearance, Mass activity, Initial progressive motility, Non-eosinophilic spermatozoa count (NESC) and post thaw motility percent. Data were analyzed by least squares technique. Group-1 was the control, whereas group-2 (treatment group) bulls were exposed to mist cooling and fanning (thrice a day 15 min each) in the dry hot summer season. Group-2 showed significantly (p < 0.01) higher value in DMT (sec), ES, PS, ITS, LS, semen volume (ml), semen color density, mass activity, initial motility, progressive motility and live sperm.

Keywords: mist cooling, Sahiwal bulls, semen quality, sexual behavior

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Authors: Beeto W. C. Leung, Nicole C. Y. Lee

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It was well known that college students experienced a high level of stress and anxiety. College athletes, a special group of college students, may even encounter a higher level of pressure and distress due to their dual endeavors in academic and athletic settings. Due to the high demands and costs of mental health services, easily accessible, web-based self-help interventions are getting more popular. The aim of the present experimental study was to examine the potential intervention effect of a mindfulness-based self-help mobile App, called 'Smiling Mind', on mindfulness and psychological well-being. Forty-six college athletes, recruited from athletic teams of two local universities in Hong Kong, were randomly assigned to the Mindfulness App Group (MAG) and the Control Group (CG). All participants were administered the Mindful Attention Awareness Scale, Geriatric Depression Scale, and Perceived Stress Scale-10 before the study (Time 1, T1) and after the 4-week intervention (Time 2, T2). MAG was requested to use the app and follow the instructions every day for at least 5 days per week. Participants were also asked to record their daily app usage time. Results showed that, for MAG, from T1 to T2, mindfulness has been increased from 3.25 to 3.92; depressive symptoms and stress has been significantly decreased from 8.6 to 5.1 and 24.8 to 13.5 respectively while for the CG, mindfulness has been decreased slightly from 3.29 to 3.13; depressive symptoms and stress has been slightly increased from 7.1 to 7.3 and 24.1 to 27.1 respectively. Three mixed-design ANOVAs with time (T1, T2) as the within-subjects factor and intervention group (MAG, CG) as the between-subjects factor revealed a main effect of time on mindfulness, F(1, 41) = 10.28, p < 0.01, depressive symptoms, F(1, 41) = 6.55, p < 0.02 and stress, F(1, 41) = 16.96, p < 0.001 respectively. Both predicted interaction between time and intervention group on mindfulness, F(1, 41) = 26.6, p < 0.001, ηp 2 =0.39, depressive symptoms, F(1, 41) = 8.00, p < 0.01, ηp 2 =0.16 and Stress F(1, 41) = 49.3, p < 0.001, ηp 2 =0.55 were significant meaning that participants using the Mindfulness Mobile App in the intervention did experienced a significant increase in mindfulness and significant decrease in depressive symptoms and perceived level of stress after the 4-week intervention when compared with the control group. The present study provided encouraging empirical support for using Smiling Mind, a self-help mobile app, to promote mindfulness and mental health in a cost-effective way. Further studies should examine the potential use of Smiling Mind in different samples, including children and adolescence, as well as, investigate the lasting effects of using the app on other psychosocial outcomes such as emotional regulations.

Keywords: college athletes, experimental study, mindfulness mobile apps, psychological well-being

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Authors: A. Goma Amira, U. E. Mahrous

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Measuring the effect of perinatal lead exposure on learning ability of offspring is considered as a sensitive and selective index for providing an early marker for central nervous system damage produced by this toxic metal. A total of 35 Sprague-Dawley adult rats were used to investigate the effect of lead acetate toxicity on behavioral patterns of adult female rats and learning ability of offspring. Rats were allotted into 4 groups, group one received 1g/l lead acetate (n=10), group two received 1.5g/l lead acetate (n=10), group three received 2g/l lead acetate in drinking water (n=10), and control group did not receive lead acetate (n=5) from 8th day of pregnancy till weaning of pups. The obtained results revealed a dose-dependent increase in the feeding time, drinking frequency, licking frequency, scratching frequency, licking litters, nest building, and retrieving frequencies, while standing time increased significantly in rats treated with 1.5g/l lead acetate than other treated groups and control. On the contrary, lying time decreased gradually in a dose-dependent manner. Moreover, movement activities were higher in rats treated with 1g/l lead acetate than other treated groups and control. Furthermore, time spent in closed arms was significantly lower in rats given 2g/l lead acetate than other treated groups, while they spent significantly much time spent in open arms than other treated groups which could be attributed to occurrence of adaptation. Furthermore, number of entries in open arms was-dose dependent. However, the ratio between open/closed arms revealed a significant decrease in rats treated with 2g/l lead acetate than the control group.

Keywords: lead toxicity, rats, learning ability, behavior

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Authors: Suha I. Al-Nassar, K. M. Adel, F. Zainab

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This work was devoted for producing ZnO nanoparticles by pulsed laser ablation (PLA) of Zn metal plate in the aqueous environment of cetyl trimethyl ammonium bromide (CTAB) using Q-Switched Nd:YAG pulsed laser with wavelength= 1064 nm, Rep. rate= 10 Hz, Pulse duration= 6 ns and laser energy 50 mJ. Solution of nanoparticles is found stable in the colloidal form for a long time. The effect of ablation time on the optical and structure of ZnO was studied is characterized by UV-visible absorption. UV-visible absorption spectrum has four peaks at 256, 259, 265, 322 nm for ablation time (5, 10, 15, and 20 sec) respectively, our results show that UV–vis spectra show a blue shift in the presence of CTAB with decrease the ablation time and blue shift indicated to get smaller size of nanoparticles. The blue shift in the absorption edge indicates the quantum confinement property of nanoparticles. Also, FTIR transmittance spectra of ZnO2 nanoparticles prepared in these states show a characteristic ZnO absorption at 435–445cm^−1.

Keywords: zinc oxide nanoparticles, CTAB solution, pulsed laser ablation technique, spectroscopic characterization

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Authors: Shreya Borthakur, Aastha Vartak

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This behavioral experiment aimed to investigate the global precedence phenomenon in a South Asian sample and its correlation with mobile screen time. The global precedence effect refers to the tendency to process overall structure before attending to specific details. Participants completed attention tasks involving global and local stimuli with varying consistencies. The results showed a tendency towards local precedence, but no significant differences in reaction times were found between consistency levels or attention conditions. However, the correlation analysis revealed that participants with higher screen time exhibited a stronger negative correlation with local attention, suggesting that excessive screen usage may impact perceptual organization. Further research is needed to explore this relationship and understand the influence of screen time on cognitive processing.

Keywords: global precedence, visual attention, perceptual organization, screen time, cognition

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Authors: ShuHui Yang, ChingChing Lu

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Measuring event-related potentials (ERPs) has been fundamental to our understanding of how people process language. One specific ERP component, a P600, has been hypothesized to be associated with syntactic reanalysis processes. We, however, propose that the P600 is not restricted to reanalysis processes, but is the index of the structural pattern processing. To investigate the structural pattern processing, we utilized the effects of stimulus degradation in structural priming. To put it another way, there was no P600 effect if the structure of the prime was the same with the structure of the target. Otherwise, there would be a P600 effect if the structure were different between the prime and the target. In the experiment, twenty-two participants were presented with four sentences of Tang poetry. All of the first two sentences, being prime, were conducted with SVO+VP. The last two sentences, being the target, were divided into three types. Type one of the targets was SVO+VP. Type two of the targets was SVO+VPVP. Type three of the targets was VP+VP. The result showed that both of the targets, SVO+VPVP and VP+VP, elicited positive-going brainwave, a P600 effect, at 600~900ms time window. Furthermore, the P600 component was lager for the target’ VP+VP’ than the target’ SVO+VPVP’. That meant the more dissimilar the structure was, the lager the P600 effect we got. These results indicate that P600 was the index of the structure processing, and it would affect the P600 effect intensity with the degrees of structural heterogeneity.

Keywords: ERPs, P600, structural pattern, structural priming, Tang poetry

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Authors: M. Wigwe, J. G Akpa, E. N Wami

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Mathematical models of the absorber of a glycol dehydration facility was developed using the principles of conservation of mass and energy. Models which predict variation of the water content of gas in mole fraction, variation of gas and liquid temperatures across the parking height were developed. These models contain contributions from bulk and diffusion flows. The effect of diffusion on the process occurring in the absorber was studied in this work. The models were validated using the initial conditions in the plant data from Company W TEG unit in Nigeria. The results obtained showed that the effect of diffusion was noticed between z=0 and z=0.004 m. A deviation from plant data of 0% was observed for the gas water content at a residence time of 20 seconds, at z=0.004 m. Similarly, deviations of 1.584% and 2.844% were observed for the gas and TEG temperatures.

Keywords: separations, absorption, simulation, dehydration, water content, triethylene glycol

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Authors: Aziz Sezgin, Yuksel Hacioglu, Nurkan Yagiz

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Sliding mode controller for a vehicle active suspension system is designed in this study. The widely used quarter car model is preferred and it is aimed to improve the ride comfort of the passengers. The effect of the actuator time delay, which may arise due to the information processing, sensors or actuator dynamics, is also taken into account during the design of the controller. A sliding mode controller was designed that has taken into account the actuator time delay by using Smith predictor. The successful performance of the designed controller is confirmed via numerical results.

Keywords: sliding mode control, active suspension system, actuator, time delay, vehicle

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Authors: Liqian Li, Yu Liu, Karen Colins

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The dose rate present in a seriously contaminated area can be indirectly determined by monitoring radiation damage to inexpensive commercial electronics, instead of deploying expensive radiation hardened sensors. EEPROMs (Electrically Erasable Read Only Memories) are a good candidate for this purpose because they are inexpensive and are sensitive to radiation exposure. When the total ionizing dose threshold is reached, an EEPROM chip will show signs of damage that can be monitored and transmitted by less susceptible electronics. The dose rate can then be determined from the known threshold dose and the exposure time, assuming the radiation field remains constant with time. Therefore, the threshold dose needs to be well understood before this method can be used. There are many factors affecting the threshold dose, such as the gamma ray energy spectrum, the operating voltage, etc. The purpose of this study was to experimentally determine how the threshold dose depends on dose rate, temperature, voltage, and duty factor. It was found that the duty factor has the strongest effect on the total ionizing dose threshold, while the effect of the other three factors that were investigated is less significant. The effect of temperature was found to be opposite to that expected to result from annealing and is yet to be understood.

Keywords: EEPROM, ionizing radiation, radiation effects on electronics, total ionizing dose, wireless sensor networks

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Authors: N. Ammouchi

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We have studied the effect of milling time on the structural and hyperfine properties of Ni45Al45Fe10 compound elaborated by mechanical alloying. The elaboration was performed by using the planetary ball mill at different milling times. The as milled powders were characterized by X-ray diffraction (XRD) and Mӧssbauer spectroscopy. From XRD diffraction spectra, we show that the β NiAl(Fe) was completely formed after 24 h of milling time. When the milling time increases, the lattice parameter increases, whereas the grain size decreases to a few nanometres and the mean level of microstrains increases. The analysis of Mӧssbauer spectra indicates that, in addition to a ferromagnetic phase, α-Fe, a paramagnetic disordered phase Ni Al (Fe) solid solution is observed after 2h and only this phase is present after 12h.

Keywords: NiAlFe, nanostructured powders, X-ray diffraction, Mӧssbauer spectroscopy

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Authors: Balwinder Singh

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Castings are produced by using aluminum alloy ADC 10 through the process of Ceramic Shell Investment Casting. Experiments are conducted as per the Taguchi L9 orthogonal array. In order to evaluate the effect of process parameters such as mould preheat temperature, preheat time, firing temperature and pouring temperature on surface roughness of ceramic shell investment castings, the Taguchi parameter design and optimization approach is used. Plots of means of significant factors and S/N ratios have been used to determine the best relationship between the responses and model parameters. It is found that the pouring temperature is the most significant factor. The best tensile strength of aluminum alloy ADC 10 is given by 150 ºC shell preheat temperature, 45 minutes preheat time, 900 ºC firing temperature, 650 ºC pouring temperature.

Keywords: investment casting, shell preheat temperature, firing temperature, Taguchi method

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Authors: Hamouda M. Mousa, M. Obaid, Chan Hee Park, Cheol Sang Kim

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The rate of copper cementation on iron rod was investigated. The study was mainly dedicated to illustrate the effect of application of electromagnetic field (EMF) on the rate of cementation. The magnetic flux was placed parallel to the iron rod and different magnetic field strength was studied. The results showed that without EMF, the rate of mass transfer was correlated by the equation: Sh= 1.36 Re0. 098 Sc0.33. The application of EMF enhanced the time required to reach high percentage copper cementation by 50%. The rate of mass transfer was correlated by the equation: Sh= 2.29 Re0. 95 Sc0.33, with applying EMF. This work illustrates that the enhancement of copper recovery in presence of EMF is due to the induced motion of Fe+n in the solution which is limited in the range of rod rotation speed of 300~900 rpm. The calculation of power consumption of EMF showed that although the application of EMF partially reduced the cementation time, the reduction of power consumption due to utilization of magnetic field is comparable to the increase in power consumed by introducing magnetic field of 2462 A T/m.

Keywords: copper cementation, electromagnetic field, copper ions, iron cylinder

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Authors: Mohammadjavad Yaghoubi, Arul Arulrajah, Mahdi M. Disfani, Suksun Horpibulsuk, Myint W. Bo, Stephen P. Darmawan

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This paper investigates the changes in the strength development of a high water content soft soil stabilised with alkaline activation of fly ash (FA) to use in deep soil mixing (DSM) technology. The content of FA was 20% by dry mass of soil, and the alkaline activator was sodium silicate (Na2SiO3). Samples were cured for 3, 7, 14, 28 and 56 days to evaluate the effect of curing time on strength development. To study the effect of adding slag (S) to the mixture on the strength development, 5% S was replaced with FA. In addition, the effect of the initial unit weight of samples on strength development was studied by preparing specimens with two different static compaction stresses. This was to replicate the field conditions where during implementing the DSM technique, the pressure on the soil while being mixed, increases with depth. Unconfined compression strength (UCS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) tests were conducted on the specimens. The results show that adding S to the FA based geopolymer activated by Na2SiO3 decreases the strength. Furthermore, samples prepared at a higher unit weight demonstrate greater strengths. Moreover, samples prepared at lower unit weight reached their final strength at about 14 days of curing, whereas the strength development continues to 56 days for specimens prepared at a higher unit weight.

Keywords: alkaline activation, curing time, fly ash, geopolymer, slag

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Authors: A. N. Moulai Khatir

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SOI-Multifin-FETs are placed to be the workhorse of the industry for the coming few generations, and thus, in a few years because their excellent transistor characteristics, ideal sub-threshold swing, low drain induced barrier lowering (DIBL) without pocket implantation, and negligible body bias dependency. The corner effect may also exist in the two lower corners; this effect is called the BOX effect, which can also occur in the direction X-Z. The electric field lines from the source and drain cross the bottom oxide and arrive in the silicon. This effect is also called DIVSB (Drain Induced Virtual Substrate Basing). The potential in the silicon film in particular near the drain is increased by the drain bias. It is similar to DIBL and result in a decrease of the threshold voltage. This work provides an understanding of the limitation of this effect by reducing the fin width for components with increased fin number.

Keywords: SOI, finFET, corner effect, dual-gate, tri-gate, BOX, multi-finFET

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Authors: Yusuf Ziya Halefoğlu

Abstract:

Phosphorescence, classically, excitation effects (radiation, electron beam, electric field, temperature, etc.) is the name given after the elimination of materials that glow in the visible region. This event continues to glow after the elimination of the effect of excitation is called phosphorescence. In this study were synthesized by the method of the combustion lanthanide doped alkaline earth aluminates. High temperature and long reaction time required and the sol-gel method of combustion according to the methods of solid state synthesis temperature lower than the short reaction time, a small particle size, convenience, and is superior in terms of being secured. Their microstructures and its effect on the photoluminescence properties were studied. Phosphorescence is derived in the dark when produced materials are held in sunlight or under ultraviolet light typically at 365-520 nm wavelength range. In this study, the optimal ratio of rare earth elements, in terms of brightness and glow duration was examined by SEM, XRD and photoluminescence analysis.

Keywords: persistence luminescence, phosphorescence, trap depth, combustion method

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Authors: Sercan Altundemir, Pinar Eribol, A. Kerem Uguz

Abstract:

Microfluidics systems allow many-large scale laboratory applications to be miniaturized on a single device in order to reduce cost and advance fluid control. Moreover, such systems enable to generate and control droplets which have a significant role on improved analysis for many chemical and biological applications. For example, they can be employed as the model for cells in microfluidic systems. In this work, the interfacial instability of two immiscible Newtonian liquids flowing in a microchannel is investigated. When two immiscible liquids are in laminar regime, a flat interface is formed between them. If a direct current electric field is applied, the interface may deform, i.e. may become unstable and it may be ruptured and form micro-droplets. First, the effect of thickness ratio, total flow rate, viscosity ratio of the silicone oil and ethylene glycol liquid couple on the critical voltage at which the interface starts to destabilize is investigated. Then the droplet sizes are measured under the effect of these parameters at various voltages. Moreover, the effect of total flow rate on the time elapsed for the interface to be ruptured to form droplets by hitting the wall of the channel is analyzed. It is observed that an increase in the viscosity or the thickness ratio of the silicone oil to the ethylene glycol has a stabilizing effect, i.e. a higher voltage is needed while the total flow rate has no effect on it. However, it is observed that an increase in the total flow rate results in shortening of the elapsed time for the interface to hit the wall. Moreover, the droplet size decreases down to 0.1 μL with an increase in the applied voltage, the viscosity ratio or the total flow rate or a decrease in the thickness ratio. In addition to these observations, two empirical models for determining the critical electric number, i.e., the dimensionless voltage and the droplet size and another model which is a combination of both models, for determining the droplet size at the critical voltage are established.

Keywords: droplet formation, electrohydrodynamics, microfluidics, two-phase flow

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Authors: Khamdan Cahyari, Gumbolo Hadi Susanto, Pratikno Hidayat, Sukirman

Abstract:

University canteen waste was used as raw material to produce biogas in Faculty of Industrial Technology, Islamic University of Indonesia. This faculty was home to more than 3000 students and lecturers who work and study for 5 days/week (8 hours/day). It produced approximately 85 ton/year organic fraction of canteen waste. Yet, this waste had been dumped for years in landfill area which cause severe environmental problems. It was proposed to utilize the waste as raw material for producing renewable energy source of biogas. This research activities was meant to investigate the effect of organic loading rate (OLR) and retention time (RT) of continuous anaerobic digestion process for 200 days. Organic loading rate was set at value 2, 3, 4 and 5 g VS/l/d whereas the retention time was adjusted at 30, 24, 18 and 14.4 days. Optimum condition was achieved at OLR 4 g VS/l/d and RT 24 days with biogas production rate between 0.75 to 1.25 liter/day (40-60% CH4). This indicated that the utilization of canteen waste to produce biogas was promising method to mitigate environmental problem of university canteen waste. Furthermore, biogas could be used as alternative energy source to supply energy demand at the university. This implementation is simultaneous solution for both waste and energy problems to achieve green campus.

Keywords: canteen waste, biogas, anaerobic digestion, university, green campus

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Authors: A. Idawaty, O. Mohamed, A. Z. Zuriati

Abstract:

This paper presents the development of an event based Discrete Event Simulation (DES) for a recovery algorithm known Backward Recovery Global Preemptive Utility Accrual Scheduling (BR_GPUAS). This algorithm implements the Backward Recovery (BR) mechanism as a fault recovery solution under the existing Time/Utility Function/ Utility Accrual (TUF/UA) scheduling domain for multiprocessor environment. The BR mechanism attempts to take the faulty tasks back to its initial safe state and then proceeds to re-execute the affected section of the faulty tasks to enable recovery. Considering that faults may occur in the components of any system; a fault tolerance system that can nullify the erroneous effect is necessary to be developed. Current TUF/UA scheduling algorithm uses the abortion recovery mechanism and it simply aborts the erroneous task as their fault recovery solution. None of the existing algorithm in TUF/UA scheduling domain in multiprocessor scheduling environment have considered the transient fault and implement the BR mechanism as a fault recovery mechanism to nullify the erroneous effect and solve the recovery problem in this domain. The developed BR_GPUAS simulator has derived the set of parameter, events and performance metrics according to a detailed analysis of the base model. Simulation results revealed that BR_GPUAS algorithm can saved almost 20-30% of the accumulated utilities making it reliable and efficient for the real-time application in the multiprocessor scheduling environment.

Keywords: real-time system (RTS), time utility function/ utility accrual (TUF/UA) scheduling, backward recovery mechanism, multiprocessor, discrete event simulation (DES)

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Authors: Mark Daniel De Luna, Ma. Katreena Pillejera, Wei-Hsin Chen

Abstract:

The raw bamboo (Phyllostachys mankinoi), with a moisture content of 13.54 % and a higher heating value (HHV) of 17.657 MJ/kg, was subjected to torrefaction under a high gravity (higee) environment using a rotating packed bed. The performance of the higee torrefaction was explored in two parts: (1) effect of rotation and temperature and (2) effect of duration on the solid yield, HHV and energy yield. By statistical analyses, the results indicated that the rotation, temperature and their interaction has a significant effect on the three responses. Same remarks on the effect of duration where when the duration (temperature and rotation) increases, the HHV increases, while the solid yield and energy yield decreases. Graphical interpretations showed that at 300 °C, the rotating speed has no evident effect on the responses. At 30-min holding time, the highest HHV reached (28.389 MJ/kg) was obtained in the most severe torrefaction condition (the rotating speed at 1800 rpm and temperature at 300 °C) with an enhancement factor of HHV corresponding to 1.61 and an energy yield of 63.51%. Upon inspection, the recommended operating condition under a 30-min holding time is at 255 °C-1800 rpm since the enhancement factor of HHV (1.53), HHV (26.988 MJ/kg), and energy yield (65.21%) values are relatively close to that of the aforementioned torrefaction condition. The Van Krevelen diagram of the torrefied biomass showed that the ratios decrease as the torrefaction intensifies, hence improving the hydrophobicity of the product. The spreads of the results of the solid yield, enhancement factor (EF) of HHV, energy yield, and H/C and O/C ratios were in accordance with the trends of the responses. Overall, from the results presented, it can be concluded that the quality of the product from the process is at par to that of coal (i.e. HHV of coal is 21-35 MJ/kg). The Fourier transform infrared (FTIR) spectroscopy results indicated that cellulose and lignin may have been degraded at a lower temperature accompanied with a high rotating speed. The results suggested that torrefaction under higee environment indicates promising process for the utilization of bamboo.

Keywords: heat transfer, high gravity environment, FTIR, rotation, rotating speed, torrefaction

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Authors: Orose Rugchati, Kanita Thanacharoenchanaphas, Sarawut Wattanawongpitak

Abstract:

In this study, the effect of electric stimulation on the quality of hot-boned beef brisket muscles was evaluated, including the tenderness, pH, temperature change, and colorant. Muscles were obtained from steers in the local slaughter house. (3 steers for each muscle), removed from the carcasses 4-hour postmortem and variable time to treated with direct current electric 1 and 5 minutes, respectively. Six different electric intensities (direct current voltage of 50, 70 and 90 Volt, pulse with 10, 20 and 40 ms) plus a control were applied to each muscle to determine the optimum treatment conditions. Hot-boned beef brisket was found to get tender with increasing treatment direct current voltage and reduction in the shear force with pulsed with electric treatment. But in a long time to treated with electric current get fading in red color and temperature increase whereas pH quite different compared to non-treated control samples.

Keywords: electric stimulation, characteristic changes, hot-boned beef brisket, potential tenderness

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