Search results for: minimum reflux ratio

Authors: Yanto Santosa, Dede Aulia Rahman, Cory Wulan, Abdul Haris Mustari

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The global demand for long-tailed macaques for medical experimentation has continued to increase. Fulfillment of Indonesian export demands has been mostly from natural habitats, based on a harvesting quota. This quota has been determined according to the total catch for a given year, and not based on consideration of any demographic parameters or physical environmental factors with regard to the animal; hence threatening the sustainability of the various populations. It is therefore necessary to formulate a method for calculating a sustainable harvesting quota, based on population parameters in natural habitats. Considering the possibility of variations in habitat characteristics and population parameters, a time series observation of demographic and physical/biotic parameters, in various habitats, was performed on 13 groups of long-tailed macaques, distributed throughout the West Java, Lampung and Yogyakarta areas of Indonesia. These provinces were selected for comparison of the influence of human/tourism activities. Data on population parameters that was collected included data on life expectancy according to age class, numbers of individuals by sex and age class, and ‘ratio of infants to reproductive females’. The estimation of population growth was based on a population dynamic growth model: the Leslie matrix. The harvesting quota was calculated as being the difference between the actual population size and the MVP (minimum viable population) for each sex and age class. Observation indicated that there were variations within group size (24 – 106 individuals), gender (sex) ratio (1:1 to 1:1.3), life expectancy value (0.30 to 0.93), and ‘ratio of infants to reproductive females’ (0.23 to 1.56). Results of subsequent calculations showed that sustainable harvesting quotas for each studied group of long-tailed macaques, ranged from 29 to 110 individuals. An estimation model of the MVP for each age class was formulated as Log Y = 0.315 + 0.884 Log Ni (number of individual on ith age class). This study also found that life expectancy for the juvenile age class was affected by the humidity under tree stands, and dietary plants’ density at sapling, pole and tree stages (equation: Y= 2.296 – 1.535 RH + 0.002 Kpcg – 0.002 Ktg – 0.001 Kphn, R2 = 89.6% with a significance value of 0.001). By contrast, for the sub-adult-adult age class, life expectancy was significantly affected by slope (equation: Y=0.377 = 0.012 Kml, R2 = 50.4%, with significance level of 0.007). The infant to reproductive female ratio was affected by humidity under tree stands, and dietary plant density at sapling and pole stages (equation: Y = -1.432 + 2.172 RH – 0.004 Kpcg + 0.003 Ktg, R2 = 82.0% with significance level of 0.001). This research confirmed the importance of population parameters in determining the minimum viable population, and that MVP varied according to habitat characteristics (especially food availability). It would be difficult therefore, to formulate a general mathematical equation model for determining a harvesting quota for the species as a whole.

Keywords: harvesting, long-tailed macaque, population, quota

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Authors: Amit K. Singh, Subhankar Sen

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The bifurcation curve of separation in steady two-dimensional viscous flow past an elliptic cylinder is studied by varying the angle of incidence (α) with different aspect ratio (ratio of minor to major axis). The solutions are based on numerical investigation, using finite element analysis, of the Navier-Stokes equations for incompressible flow. Results are presented for Reynolds number up to 50 and angle of incidence varies from 0° to 90°. Range of aspect ratio (Ar) is from 0.1 to 1 (in steps of 0.1) and flow is considered as unbounded flow. Bifurcation curve represents the locus of Reynolds numbers (Res) at which flow detaches or separates from the surface of the body at a given α and Ar. In earlier studies, effect of Ar on laminar separation curve or bifurcation curve is limited for Ar = 0.1, 0.2, 0.5 and 0.8. Some results are also available at α = 90° and 45°. The present study attempts to provide a systematic data and clear understanding on the effect of Ar at bifurcation curve and its point of maxima. In addition, issues regarding location of separation angle and maximum ratio of coefficient of lift to drag are studied. We found that nature of curve, separation angle and maximum ratio of lift to drag changes considerably with respect to change in Ar.

Keywords: aspect ratio, bifurcation curve, elliptic cylinder, GMRES, stabilized finite-element

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Authors: H. Lee, J. Park

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In this present study, for the first time, we retrieved the Formaldehyde (HCHO) Vertical Column Density (HCHOVCD) using Pandora instruments in Seoul, a megacity in northeast Asia, for the period between 2012 and 2014 and investigated the temporal characteristics of HCHOVCD. HCHO Slant Column Density (HCHOSCD) was obtained using the Differential Optical Absorption Spectroscopy (DOAS) method. HCHOSCD was converted to HCHOVCD using geometric Air Mass Factor (AMFG) as Pandora is the direct-sun measurement. The HCHOVCDs is low at 12:00 Local Time (LT) and is high in the morning (10:00 LT) and late afternoon (16:00 LT) except for winter. The maximum (minimum) values of Pandora HCHOVCD are 2.68×1016 (1.63×10¹⁶), 3.19×10¹⁶ (2.23×10¹⁶), 2.00×10¹⁶ (1.26×10¹⁶), and 1.63×10¹⁶ (0.82×10¹⁶) molecules cm⁻² in spring, summer, autumn, and winter, respectively. In terms of seasonal variations, HCHOVCD was high in summer and low in winter which implies that photo-oxidation plays an important role in HCHO production in Seoul. In comparison with the Ozone Monitoring Instrument (OMI) measurements, the HCHOVCDs from the OMI are lower than those from Pandora. The correlation coefficient (R) between monthly HCHOVCDs values from Pandora and OMI is 0.61, with slop of 0.35. Furthermore, to understand HCHO mixing ratio within Planetary Boundary Layer (PBL) in Seoul, we converted Pandora HCHOVCDs to HCHO mixing ratio in the PBL using several meteorological input data from the Atmospheric InfraRed Sounder (AIRS). Seasonal HCHO mixing ratio in PBL converted from Pandora (OMI) HCHOVCDs are estimated to be 6.57 (5.17), 7.08 (6.68), 7.60 (4.70), and 5.00 (4.76) ppbv in spring, summer, autumn, and winter, respectively.

Keywords: formaldehyde, OMI, Pandora, remote sensing

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Authors: Ferruh Taspinar, Ismail Saracoglu, Emrah Afsar, Eda O. Okur, Gulce K. Seyyar, Gamze Kurt, Betul Taspinar

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Although it is thought that abdominal adiposity is one of the risk factor for postural deviation, such as increased lumbar lordosis, the body mass index is not sufficient to indicate effects of abdominal adiposity on spinal alignment and postural changes. The aim of this study was to investigate the correlation with detailed body composition and spine alignment in healthy young adults. This cross-sectional study was conducted with sixty seven healthy volunteers (37 men and 30 women) whose ages ranged between 19 and 27 years. All participants’ sagittal spinal curvatures of lumbar and thoracic region were measured via Spinal mouse® (Idiag, Fehraltorf, Switzerland). Also, body composition analysis (whole body fat ratio, whole body muscle ratio, abdominal fat ratio, and trunk muscle ratio) estimation by means of bioelectrical impedance was evaluated via Tanita Bc 418 Ma Segmental Body Composition Analyser (Tanita, Japan). Pearson’s correlation was used to analysis among the variables. The mean lumbar lordosis and thoracic kyphosis angles were 21.02°±9.39, 41.50°±7.97, respectively. Statistically analysis showed a significant positive correlation between whole body fat ratio and lumbar lordosis angle (r=0.28, p=0.02). Similarly, there was a positive correlation between abdominal fat ratio and lumbar lordosis angle (r=0.27, p=0.03). The thoracic kyphosis angle showed also positive correlation with whole body fat ratio (r=0.33, p=0.00) and abdominal fat ratio (r=0.40, p=0.01). The whole body muscle ratio showed negative correlation between lumbar lordosis (r=-0.28, p=0.02) and thoracic kyphosis angles (r=-0.33, p=0.00), although there was no statistically correlation between trunk muscle ratio, lumbar and thoracic curvatures (p>0.05). The study demonstrated that an increase of fat ratio and decrease of muscle ratio in abdominal region or whole body shifts the spinal alignment which may adversely affect the spinal loading. Therefore, whole body composition should be taken into account in spine rehabilitation.

Keywords: body composition, lumbar lordosis, spinal alignment, thoracic kyphosis

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Authors: A. Kaćunić, M. Ćosić, N. Kuzmanić

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Interaction between mixing and crystallization is often ignored despite the fact that it affects almost every aspect of the operation including nucleation, growth, and maintenance of the crystal slurry. This is especially pronounced in multiple impeller systems where flow complexity is increased. By choosing proper mixing parameters, what closely depends on the knowledge of the hydrodynamics in a mixing vessel, the process of batch cooling crystallization may considerably be improved. The values that render useful information when making this choice are mixing time and power consumption. The predominant motivation for this work was to investigate the extent to which radial dual impeller configuration influences mixing time, power consumption and consequently the values of metastable zone width and nucleation rate. In this research, crystallization of borax was conducted in a 15 dm3 baffled batch cooling crystallizer with an aspect ratio (H/T) of 1.3. Mixing was performed using two straight blade turbines (4-SBT) mounted on the same shaft that generated radial fluid flow. Experiments were conducted at different values of N/NJS ratio (impeller speed/ minimum impeller speed for complete suspension), D/T ratio (impeller diameter/crystallizer diameter), c/D ratio (lower impeller off-bottom clearance/impeller diameter), and s/D ratio (spacing between impellers/impeller diameter). Mother liquor was saturated at 30°C and was cooled at the rate of 6°C/h. Its concentration was monitored in line by Na-ion selective electrode. From the values of supersaturation that was monitored continuously over process time, it was possible to determine the metastable zone width and subsequently the nucleation rate using the Mersmann’s nucleation criterion. For all applied dual impeller configurations, the mixing time was determined by potentiometric method using a pulse technique, while the power consumption was determined using a torque meter produced by Himmelstein & Co. Results obtained in this investigation show that dual impeller configuration significantly influences the values of mixing time, power consumption as well as the metastable zone width and nucleation rate. A special attention should be addressed to the impeller spacing considering the flow interaction that could be more or less pronounced depending on the spacing value.

Keywords: dual impeller crystallizer, mixing time, power consumption, metastable zone width, nucleation rate

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Authors: Hemanth K. Balaga, Prakash Nanthagopalan

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Every year a huge amount of paper gets discarded of which only a minute fraction is being recycled and the rest gets dumped as landfills. Paper fibres can be recycled only a limited number of times before they become too short or weak to make high quality recycled paper. This eventually adds to the already big figures of waste paper that is being generated and not recycled. It would be advantageous if this prodigious amount of waste can be utilized as a low-cost sustainable construction material and make it as a value added product. The generic term for the material under investigation is paper-concrete. This is a fibrous mix made of Portland cement, water and pulped paper and/or other aggregates. The advantages of this material include light weight, good heat and sound insulation capability and resistance to flame. The disadvantages include low strength compared to conventional concrete and its hydrophilic nature. The properties vary with the variation of cement and paper content in the mix. In the present study, Portland Pozzolona Cement and news print paper were used for the preparation of paper concrete cubes. Initially, investigations were performed to determine the minimum soaking period required for the softening of the paper fibres. Further different methodologies were explored for proper blending of the pulp with cement paste. The properties of paper concrete vary with the variation of cement to paper to water ratio. The study mainly addresses the parameters of strength and weight loss of the concrete cubes with age and the time that is required for the dry paper fibres to become soft enough in water to bond with the cement. The variation of compressive strength with cement content, water content, and time was studied. The water loss of the cubes with time and the minimum time required for the softening of paper fibres were investigated .Results indicate that the material loses 25-50 percent of the initial weight at the end of 28 days, and a maximum 28 day compressive strength (cubes) of 5.4 Mpa was obtained.

Keywords: soaking time, difference water, minimum water content, maximum water content

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Authors: Hui-Chuan Lu

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In a perfect secret-sharing scheme, a dealer distributes a secret among a set of participants in such a way that only qualified subsets of participants can recover the secret and the joint share of the participants in any unqualified subset is statistically independent of the secret. The access structure of the scheme refers to the collection of all qualified subsets. In a graph-based access structures, each vertex of a graph G represents a participant and each edge of G represents a minimal qualified subset. The average information ratio of a perfect secret-sharing scheme realizing a given access structure is the ratio of the average length of the shares given to the participants to the length of the secret. The infimum of the average information ratio of all possible perfect secret-sharing schemes realizing an access structure is called the optimal average information ratio of that access structure. We study the optimal average information ratio of the access structures based on bipartite graphs. Based on some previous results, we give a bound on the optimal average information ratio for all bipartite graphs of girth at least six. This bound is the best possible for some classes of bipartite graphs using our approach.

Keywords: secret-sharing scheme, average information ratio, star covering, deduction, core cluster

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Authors: M. Benachour, N. Benachour, M. Benguediab

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In this investigation, variation of cyclic loading effect on fatigue crack growth is studied. This study is performed on 2024 T351 and 7050-T74 aluminum alloys, used in aeronautical structures. The propagation model used in this study is NASGRO model. In constant amplitude loading (CA), the effect of stress ratio has been investigated. Fatigue life and fatigue crack growth rate were affected by this factor. Results showed an increasing in fatigue crack growth rates (FCGRs) with increasing stress ratio. Variable amplitude loading (VAL) can take many forms i.e with a single overload, overload band etc. The shape of these loads affects strongly the fracture life and FCGRs. The application of a single overload (ORL) decrease the FCGR and increase the delay crack length caused by the formation of a larger plastic zone compared to the plastic zone due without VAL. The fatigue behavior of the both material under single overload has been compared.

Keywords: fatigue crack growth, overload ratio, stress ratio, generalized willenborg model, retardation, al-alloys

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Authors: Robab Abdolkhani, Farzin Halabchi, Reza Safdari, Goli Arji

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Background and purpose: The quality of health record depends on the quality of its content and proper documentation. Minimum data set makes a standard method for collecting key data elements that make them easy to understand and enable comparison. The aim of this study was to determine the minimum data set for Iranian athletes’ health records. Methods: This study is an applied research of a descriptive comparative type which was carried out in 2013. By using internal and external forms of documentation, a checklist was created that included data elements of athletes health record and was subjected to debate in Delphi method by experts in the field of sports medicine and health information management. Results: From 97 elements which were subjected to discussion, 85 elements by more than 75 percent of the participants (as the main elements) and 12 elements by 50 to 75 percent of the participants (as the proposed elements) were agreed upon. In about 97 elements of the case, there was no significant difference between responses of alumni groups of sport pathology and sports medicine specialists with medical record, medical informatics and information management professionals. Conclusion: Minimum data set of Iranian athletes’ health record with four information categories including demographic information, health history, assessment and treatment plan was presented. The proposed model is available for manual and electronic medical records.

Keywords: Documentation, Health record, Minimum data set, Sports medicine

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Authors: Seyed Abbas Tabatabaei, Marjan Naderan Tahan, Arman Kadkhodai

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An efficient optimization approach, called feasible gate (FG), is developed to enhance the computation efficiency and solution quality of the previously developed highway alignment optimization (HAO) model. This approach seeks to realistically represent various user preferences and environmentally sensitive areas and consider them along with geometric design constraints in the optimization process. This is done by avoiding the generation of infeasible solutions that violate various constraints and thus focusing the search on the feasible solutions. The proposed method is simple, but improves significantly the model’s computation time and solution quality. On the other, highway alignment optimization through Feasible Gates, eventuates only economic model by considering minimum design constrains includes minimum reduce of circular curves, minimum length of vertical curves and road maximum gradient. This modelling can reduce passenger comfort and road safety. In most of highway optimization models, by adding penalty function for each constraint, final result handles to satisfy minimum constraint. In this paper, we want to propose a safety-function solution by introducing gift function.

Keywords: safety, highway geometry, optimization, alignment

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Authors: Zhenqiu Liu

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Visualizing the heterogeneity within cell-populations for single-cell RNA-seq data is crucial for studying the functional diversity of a cell. However, because of the high level of noises, outlier, and dropouts, it is very challenging to measure the cell-to-cell similarity (distance), visualize and cluster the data in a low-dimension. Minimum volume embedding (MVE) projects the data into a lower-dimensional space and is a promising tool for data visualization. However, it is computationally inefficient to solve a semi-definite programming (SDP) when the sample size is large. Therefore, it is not applicable to single-cell RNA-seq data with thousands of samples. In this paper, we develop an efficient algorithm with an accelerated proximal gradient method and visualize the single-cell RNA-seq data efficiently. We demonstrate that the proposed approach separates known subpopulations more accurately in single-cell data sets than other existing dimension reduction methods.

Keywords: single-cell RNA-seq, minimum volume embedding, visualization, accelerated proximal gradient method

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Authors: Dhyaalddin Bahaalddin Noori Zangana

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This study involves the behavior of reinforced sand under a square footing. A series of bearing capacity tests were performed on a small-scale laboratory model, which filled with a poorly-graded homogenous bed of sand, which was placed in a medium dense state using sand raining technique. The sand was reinforced with 40 mm wide household aluminum foil strips. The main studied parameters was to consider the effect of reinforcing strip length, with various linear density of reinforcement, number of reinforcement layers and depth of top layer of reinforcement below the footing, on load-settlement behavior, bearing capacity ratio and settlement reduction factor. The relation of load-settlement generally showed similar trend in all the tests. Failure was defined as settlement equal to 10% of the footing width. The recommended optimum reinforcing strip length, linear density of reinforcement, number of reinforcement layers and depth of top layer of reinforcing strips that give the maximum bearing capacity improvement and minimum settlement reduction factor were presented and discussed. Different bearing capacity ration versus length of the reinforcing strips and settlement reduction factor versus length of the reinforcing strips relations at failure were showed improvement of bearing capacity ratio by a factor of 3.82 and reduction of settlement reduction factor by a factor of 0.813. The optimum length of reinforcement was found to be 7.5 times the footing width.

Keywords: square footing, relative density, linear density of reinforcement, bearing capacity ratio, load-settlement behaviour

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Authors: Hammam Aljabri, Hong G. Im

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Hydrogen is a promising future fuel to support the transition of the energy sector toward carbon neutrality. The direct utilization of H2 in Internal Combustion Engines (ICEs) is possible, and this technology faces mainly two challenges; high NOx emissions and severe knocking at mid to high loads. In this study, we numerically investigated the potential of H2 combustion in a truck-size engine operated in SI mode. To mitigate the knocking nature of H2 combustion, we have focused on studying the effects of three primary parameters; the compression ratio (CR), the air-fuel ratio, and the spark time. The baseline case was set using a CR of 16.5 and an equivalence ratio of 0.35. In simulations, the auto-ignition tendency was evaluated based on the maximum pressure rise rate and the local pressure fluctuations at the monitoring points set along the wall of the combustion chamber. To mitigate the auto-ignition tendency while enabling a wider range of engine operation, the effect of lowering the compression ratio was assessed. The results indicate that by lowering the compression ratio from 16.5:1 to 12.5:1, an indicated thermal efficiency of 47.5% can be achieved. Aiming to restrain the auto-ignition while maintaining good efficiency, a reduction in the equivalence ratio was examined under different compression ratios. The result indicates that higher compression ratios will require lower equivalence ratios, and due to practical limitations, a lower equivalence ratio of 0.25 was set as the limit. Using a compression ratio of 13.5 combined with an equivalence ratio of 0.3 resulted in an indicated thermal efficiency of 48.6%, that is, at a fixed spark time. It is found that under such lean conditions, the incomplete combustion losses and exhaust losses were high. Thus, advancing the spark time was assessed as a possible solution. The results demonstrated the advantages of advancing the spark time, where an indicated thermal efficiency exceeding 50% was achieved using a compression ratio of 14.5:1 and an equivalence ratio of 0.25.

Keywords: hydrogen, combustion, engine knock, SI engine

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Authors: Kharisma Utomo Mulyodinoto, Suwarno, A. Abu-Siada

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Dissolved Gas Analysis is one of impressive technique to detect and predict internal fault of transformers by using gas generated by transformer oil sample. A number of methods are used to interpret the dissolved gas from transformer oil sample: Doernenberg Ratio Method, IEC (International Electrotechnical Commission) Ratio Method, and Duval Triangle Method. While the assessment of dissolved gas within transformer oil samples has been standardized over the past two decades, analysis of the results is not always straight forward as it depends on personnel expertise more than mathematical formulas. To get over this limitation, this paper is aimed at improving the interpretation of Doernenberg Ratio Method, IEC Ratio Method, and Duval Triangle Method using Two Stages Adaptive Neuro-Fuzzy Inference System (ANFIS). Dissolved gas analysis data from 520 faulty transformers was analyzed to establish the proposed ANFIS model. Results show that the developed ANFIS model is accurate and can standardize the dissolved gas interpretation process with accuracy higher than 90%.

Keywords: ANFIS, dissolved gas analysis, Doernenberg ratio method, Duval triangular method, IEC ratio method, transformer

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Authors: Harold P. Pareja

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This paper answers the question whether the minimum age of criminal responsibility under the Republic Act No. 9344 (Juvenile Justice Act) as amended by Republic Act No. 10630 should be lowered to 15 years of age or not in the light of international standards and domestic concerns both of which will definitely elicit strong views. It also explores the specific provision on the minimum age of criminal responsibility under the Republic Act No. 9344 (Juvenile Justice Act) and traces the bases of such law by discussing its presented evidences and justifications as reflected in the records of proceedings in the law-making phase. On one hand, the paper discusses the impact of lowering the minimum age to the state of juvenile delinquencies and to the rate of rehabilitation for those CICL who have undergone the DSWD-supervised recovery programs. On the other hand, it presents its impact to the international community specifically to the Committee of the Rights of the Child and the UNICEF considering that the even the current minimum age set in RA 9344 is lower than the international standards. Document review and content analysis are the major research tools. Primary and secondary sources were used as references such as Philippine laws on juvenile justice and from the different states international think-tanks. The absence of reliable evidences on criminal capacity made the arguments in increasing the MACR in the harder position. Studies on criminal capacity vary from different countries and from practitioners in in the fields of psychology, psychiatry and forensics. Juvenile delinquency is mainly contributed by poverty and dysfunctional families. On the other hand, the science of the criminal mind specifically among children has not been established yet. Philippines have the legal obligations to be faithful to the CRC and other related international instruments for the juvenile justice and welfare system. Decreasing MACR does not only send wrong message to the international community but the Philippines is violating its own laws.

Keywords: juvenile justice, minimum age of responsibility (MAR), juvenile justice act of the Philippines, children in conflict with the law, international standards on juvenile justice

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Authors: M. Z. Abdul Rofiq Badril Rizal

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This research is aimed to know the improvement of students’ English writing skill by using brainstorming technique. The technique used in writing is able to help the students’ difficulties in generating ideas and to lead the students to arrange the ideas well as well as to focus on the topic developed in writing. The research method used is classroom action research. The data sources of the research are an English teacher who acts as an observer and the students of class X.MIA5 consist of 35 students. The test result and observation are collected as the data in this research. Based on the research result in cycle one, the percentage of students who reach minimum accomplishment criteria (MAC) is 76.31%. It shows that the cycle must be continued to cycle two because the aim of the research has not accomplished, all of the students’ scores have not reached MAC yet. After continuing the research to cycle two and the weaknesses are improved, the process of teaching and learning runs better. At the test which is conducted in the end of learning process in cycle two, all of the students reach the minimum score and above 76 based on the minimum accomplishment criteria. It means the research has been successful and the percentage of students who reach minimum accomplishment criteria is 100%. Therefore, the writer concludes that brainstorming technique is able to improve the students’ English writing skill at the tenth grade of SMAN 2 Jember.

Keywords: brainstorming technique, improving, writing skill, knowledge and innovation engineering

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Authors: Kevin Spencer G. Anglim, Zhenyu Zhang, Qingbin Gao

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Reusable launch vehicles (RLVs) present a more environmentally-friendly approach to accessing space when compared to traditional launch vehicles that are discarded after each flight. This paper studies the recyclable nature of RLVs by presenting a solution method for determining minimum-fuel optimal trajectories using principles from optimal control theory and particle swarm optimization (PSO). This problem is formulated as a minimum-landing error powered descent problem where it is desired to move the RLV from a fixed set of initial conditions to three different sets of terminal conditions. However, unlike other powered descent studies, this paper considers the highly nonlinear effects caused by atmospheric drag, which are often ignored for studies on the Moon or on Mars. Rather than optimizing the controls directly, the throttle control is assumed to be bang-off-bang with a predetermined thrust direction for each phase of flight. The PSO method is verified in a one-dimensional comparison study, and it is then applied to the two-dimensional cases, the results of which are illustrated.

Keywords: minimum-fuel optimal trajectory, particle swarm optimization, reusable rocket, SpaceX

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Authors: J. A. Louw Coetzee, Josua P. Meyer

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The thermodynamic properties of different refrigerants in combination with the variation in geometrical properties (hydraulic diameter, aspect ratio, and inclination angle) of a rectangular microchannel determine the two-phase frictional pressure gradient. The effect of aspect ratio on frictional pressure drop had not been investigated enough during adiabatic two-phase flow and condensation in rectangular microchannels. This experimental study was concerned with measurement of the frictional pressure gradient in a rectangular microchannel, with hydraulic diameter of 900 μm. The aspect ratio of this microchannel was varied over a range that stretched from 0.3 to 3 in order to capture the effect of aspect ratio variation. A commonly used refrigerant, R134a, was used in the tests that spanned over a mass flux range of 100 to 1000 kg m-2 s-1 as well as the whole vapour quality range. This study formed part of a refrigerant condensation experiment and was therefore conducted at a saturation temperature of 40 °C. The study found that there was little influence of the aspect ratio on the frictional pressure drop at the test conditions. The data was compared to some of the well known micro- and macro-channel two-phase pressure drop correlations. Most of the separated flow correlations predicted the pressure drop data well at mass fluxes larger than 400 kg m-2 s-1 and vapour qualities above 0.2.

Keywords: aspect ratio, microchannel, two-phase, pressure gradient

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Authors: A. Benmerkhi, A. Bounouioua, M. Bouchemat, T. Bouchemat

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In this paper, we present a numerical optical properties of a triangular periodic lattice of elliptical air holes. We report the influence of the ratio (semi-major axis length of elliptical hole to the filling ratio) on the photonic band gap. Then by using the finite difference time domain (FDTD) algorithm, the resonant wavelength of the point defect microcavities in a two-dimensional photonic crystal (PC) shifts towards the low wavelengths with significantly increased filing ratio. It can be noted that the Q factor is gradually changed to higher when the filling ratio increases. It is due to an increase in reflectivity of the PC mirror. Also we theoretically investigate the H1 cavity, where the value of semi-major axis (Rx) of the six holes surrounding the cavity are fixed at 0.5a and the Rx of the two edge air holes are fixed at the optimum value of 0.52a. The highest Q factor of 4.1359 × 10⁶ is achieved at the resonant mode located at λ = 1.4970 µm.

Keywords: photonic crystal, microcavity, filling ratio, elliptical holes

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Authors: B. V. Lande, Suhas Kongare

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Fuel blend of alcohol and conventional hydrocarbon fuels for a spark ignition engine can increase the fuel octane rating and the power for a given engine displacement and compression ratio. The greatest advantage of ethanol as a fuel in SI Engines is its high octane number. The efficiency of an SI engine that is the ability to convert fuel energy to mechanical energy, mainly depends on the compression ratio. It is, therefore, an advantage to increase this as much as possible. The major restraint is the fuel octane number – high octane fuels can be used with high compression ratios, thus yielding higher energy efficiency. This work investigates to suggest suitable ethanol gasoline blend and compression ratio for single cylinder four strokes SI Engine on the basis of performance and exhaust emissions. A single cylinder four stroke SI Engine was tested with different blend of ethanol – gasoline like E5 (5% ethanol +95% gasoline), E10 (10% ethanol + 90% gasoline) E15 (15% ethanol + 85% petrol) and E20 ( 20% + 80% gasoline) with Variable compression ratio. The performance parameter evaluated BSFC, Brake thermal efficiency and also exhaust emission CO2, Co & HC%. The result showed that higher compression ratio improved engine Performance and reduction in exhaust emission.

Keywords: blend, compression ratio, ethanol, performance, blend

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Authors: Ho Yuan-Hong, Huang Chiung-Ju

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This study conducts simulation analyses to find the optimal debt ceiling of Taiwan, while factoring in welfare maximization under a dynamic stochastic general equilibrium framework. The simulation is based on Taiwan's 2001 to 2011 economic data and shows that welfare is maximized at a "debt"⁄"GDP" ratio of 0.2, increases in the "debt"⁄"GDP " ratio leads to increases in both tax and interest rates and decreases in the consumption ratio and working hours. The study results indicate that the optimal debt ceiling of Taiwan is 20% of GDP, where if the "debt"⁄"GDP" ratio is greater than 40%, the welfare will be negative and result in welfare loss.

Keywords: debt sustainability, optimal debt ceiling, dynamic stochastic general equilibrium, welfare maximization

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Authors: Huanhuan Zhao, Bryony J. James

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The relationship between the non-fat solid ratio and bloom formation in untempered chocolate was investigated using two types of chocolate: model chocolate made of varying cocoa powder ratios (46, 49.5 and 53%) and cocoa butter, and commercial Lindt chocolate with varying cocoa content (70, 85 and 90%). X-ray diffraction and colour measurement techniques were used to examine the polymorphism of cocoa butter and the surface whiteness index (WI), respectively. The polymorphic transformation of cocoa butter was highly correlated with the changes of WI during 30 days of storage since it led to the redistribution of fat within the chocolate matrix and resulted in a bloomed surface. The change in WI indicated a similar bloom rate in the chocolates, but the model chocolates with a higher cocoa powder ratio had more pronounced total bloom. This is due to a higher ratio of non-fat solid particles on the surface resulting in microscopic changes in morphology. The ratio of non-fat solids is an important factor in determining the extent of bloom but not the bloom rate.

Keywords: untempered chocolate, microstructure of bloom, polymorphic transformation, surface whiteness

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Authors: Sewon Kim, Chang Yeop Lee, Minjun Kwon

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This study is aiming at establishing the relationship between the optical signal of flame and an equivalent ratio of flame. In this experiment, flame optical signal in a furnace is measured using photodiode. The combustion system which is composed of metal fiber burner and vertical furnace and flame chemiluminescence is measured at various experimental conditions. In this study, the flame chemiluminescence of laminar premixed flame is measured by using commercially available photodiode. It is experimentally investigated the relationship between equivalent ratio and photodiode signal. In addition, The strategy of combustion control method is proposed by using the optical signal and fuel pressure. The results showed that certain relationship between optical data of photodiode and equivalence ratio exists and this leads to the successful application of this system for instantaneous measurement of equivalence ration of the combustion system.

Keywords: flame chemiluminescence, photo diode, equivalence ratio, combustion control

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Authors: Saima Ali, Liaqat Ali, Nasir Orakzai

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Background: Hydronephrosis is the most common abnormal finding in the urinary tract on prenatal screening with Ultrasonography. The prenatal hydronephrosis is a diagnostic dilemma in differentiating between obstructive variant versus physiologic hydronephrosis. The assessment and prompt diagnosis of prenatal hydronephrosis is important because of the fact that untreated obstructive hydronephrosis usually leads to recurrent UTI, Urosepsis, deterioration of renal functions, non-functioning kidneys, and even end-stage renal disease. Objectives: To determine the etiology and outcome of postnatal treatment of children with prenatal hydronephrosis in two teaching hospitals of Khyber Pakhtunkhwa (KPK) Methods: It is a multicentric descriptive study that was conducted in department of Paediatrics in Kuwait teaching hospital Peshawar and Department of Urology in Institute of Kidney Diseases Hayatabad Medical Complex Peshawar from January 2008 till December 2010. Total numbers of 64 neonates were included in the study with the mean follow-up of 14.5 months. All the diagnostic data in prenatal, postnatal data, and operative and non-operative data were collected on structured Proforma and was analyzed on SPSS version 17. Results: Out of 64 patients, 39 (60.9 %) were male while 25 were female. 52 patients had unilateral while 12 patients had bilateral hydronephrosis. Based upon prenatal USG in term of AP diameter, 37 (57 %) patients had mild hydronephrosis (5-10 mm AP diameter), 14 patients had moderate hydronephrosis (10-15 mm AP diameter) while 13 patients had gross hydronephrosis (More than 15mm). Regarding etiology, 44(76 %) patients were labeled as physiologic hydronephrosis, 11 patients (9.3%) with PUJ obstruction, 5 patients with Vesicoureteric reflux (VUR) and 4 patients with posterior urethral valves. Surgery was performed in total of 15 (23.4%) patients that included open Pyeloplasty in 11 patients, Vesicostomy followed by posterior valve fulguration in 4 patients. All the patients of VUR treated medically. The severity in the grade of prenatal hydronephrosis is significantly associated with the need for definitive urological surgery p < 0.005. Ancillary procedures like percutaneous nephrostomy (PCN) were inserted 7 patients. Conclusions: Prenatal hydronephrosis is a common ailment associated with significant morbidity. Physiological Hydronephrosis and VUR can be successfully treated with medical treatment. However obstructive PUJ obstructions and posterior urethral valves require surgical correction with a good success rate.

Keywords: prenatal hydronephrosis, Pelviureteric Junction (PUJ) Obstruction, vesicoureteric reflux, posterior urethral valve, renography

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Authors: Tomotaka Aoki, Isao Tomita

Abstract:

We examined the on-off ratio and frequency components of output signals from an electron-interference device made of GaAs/AlₓGa₁₋ₓAs by solving the time-dependent Schrödinger's equation on conducting electrons in the channel waveguide of the device. For electron-wave modulation, a periodic voltage of frequency f was applied to the channel. Furthermore, we examined the voltage-amplitude dependence of the signals in time and frequency domains and found that large applied voltage deformed the output-signal waveform and created additional side modes (frequencies) near the modulation frequency f and that there was a trade-off between on-off ratio and side-mode creation.

Keywords: electrical conduction, electron interference, frequency spectrum, on-off ratio

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Authors: S. S. Chong, A. R. Abdul Aziz, S. W. Harun, H. Arof

Abstract:

A miniaturized non-adiabatic silica microfiber is proposed for biological oxygen demand (BOD) ratio chemical oxygen demand (COD) sensing for the first time. BOD and COD are two main parameters to justify quality of wastewater. A ratio, BOD:COD can usually be established between the two analytical methods once COD and BOD value has been gathered. This ratio plays a vital role to determine appropriate strategy in wastewater treatment. A non-adiabatic microfiber sensor was formed by tapering the SMF to generate evanescent field where sensitive to perturbation of sensing medium. Because difference ratio BOD and COD contain in solution, this may induced changes of effective refractive index between microfiber and sensing medium. Attenuation wavelength shift to right with 0.5 nm and 3.5 nm while BOD:COD equal to 0.09 and 0.18 respectively. Significance difference wavelength shift may relate with the biodegradability of analyte. This proposed sensor is compact, reliable and feasible to determine the BOD:COD. Further research and investigation should be proceeded to enhance sensitivity and precision of the sensor for several of wastewater online monitoring.

Keywords: non-adiabatic fiber sensor, environmental sensing, biodegradability, evanescent field

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Authors: N. Nagalakshmi, Indira Bairy, M. Atulya, Jesil Mathew

Abstract:

S. aureus has the ability to colonize and form biofilms on implanted biomaterials, which is difficult to disrupt, and current antimicrobial therapies for biofilms have largely proven unsuccessful in complete eradication of biofilm. The present study is aimed to determine the lysostaphin activity against biofilm producing MRSA clinical strains. The minimum biofilm inhibition activity of lysostaphin was studied against twelve strong biofilm producing isolates. The biofilm was produced in 96-wells micro-titer plate and biofilm was treated with lysostaphin (0.5 to 16 µg/ml), vancomycin (0.5 to 64 µg/ml) and linezolid (0.5 to 64 µg/ml). The biofilm inhibitory concentration of lysostaphin was found between 4 to 8 µg/ml whereas vancomycin and linezolid inhibited at concentration between 32 to 64 µg/ml. Results indicate that lysostaphin as potential antimicrobial activity against biofilm at lower concentration is comparable with routine antibiotics like vancomycin and linezolid.

Keywords: biofilm, lysostaphin, MRSA, minimum biofilm inhibitory concentration

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Authors: I. Ibrahim, A. Mann

Abstract:

Phytochemical screening of crude Chrysanthlum Indicum revealed the presence of carbohydrates, flavonoids, saponins, tannins, alkanoids, steroidal nucleus and cardiac glycosides. The extract was evaluated against some pathogenic organisms by agar dilution method. The minimum inhibitory concentration and minimum bacteriocidal concentration (MBC) of the active extract of Chrysanthlum Indicum shows that its extract could be a potential source of antimicrobial agents.

Keywords: extract, phytochemicals, antimicrobial, antibacterial, Chrysanthlum indicum

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Authors: Godwin Chigozie Okpara, Eugene Iheanacho

Abstract:

This paper examined the dynamic behavior of stock market development and the growth of Nigerian economy. The variables; market capitalization ratio, turnover ratio and liquidity proxies by the ratio of market capitalization to gross domestic product were sourced and computed from the Nigerian stock exchange fact books and the CBN statistical bulletin of the Central Bank of Nigeria. The variables were tested and found stationary and cointregrated using the augumented Dickey Fuller unit root test and the Johnson cointegration test respectively. The dynamic behavior of the stock market development model was verified using the error correction model. The result shows that about 0.4l percent of the short run deviation is corrected every year and also reveals that market capitalization ratio and market liquidity are positive and significant function of economic growth. In other words market capitalization ratio and liquidity positively and significantly impact economic growth. Market development variables such as turnover ratio and market restriction can exert positive but insignificant impact on the growth of the economy suggesting that securities transaction relative to the size of the securities market are not high enough to significantly engender economic growth in Nigeria. In the light of this, the researchers recommend that the regulatory body as well as the government, should provide a conducive environment capable of encouraging the growth and development of the stock market. This if well articulated will enhance the market turnover and the growth of the economy.

Keywords: market capitalization ratio, turnover ratio, liquidity, unit root test, cointegration

Procedia PDF Downloads 300

Authors: Kalpana Jamdhade, Anita Chorey, Bharti Tijare, V. M. Bhale

Abstract:

A field experiment was conducted during summer season of 2011 at Agronomy research farm, Dr. PDKV, Akola, to study the effect of irrigation regime and nitrogen levels on growth and productivity of summer sesame. The experiment was laid out in split plot Design in which three irrigation scheduling on the basis of IW/CPE ratio viz., irrigation at 0.6, 0.8 and 1.0 IW/CPE ratios (I1, I2 and I3, respectively) and one irrigation scheduling based on critical growth stages of sesame (I4), in main plot and three nitrogen levels 0, 30 and 60 kg N ha-1 (N0, N1 and N2, respectively) in subplot. The result showed that plant height, number of leaves plant-1, leaf area and dry matter accumulation were maximum in irrigation scheduling at 1.0 IW/CPE ratio, which significantly superior over 0.6 IW/CPE ratio and irrigation at critical growth stages but were statistically at par with irrigation at 0.8 IW/CPE ratio. Nitrogen levels, application of 60 kg N ha-1 was recorded significantly superior all growth parameters over treatment 30 kg N ha-1 and 0 kg N ha-1. In case of yield attributes viz., No. of capsules plant-1, Test wt., grain yield and Stalk yield (qha-1) were maximum in irrigation scheduling at 1.0 IW/CPE ratio and were significantly superior over 0.8 IW/CPE ratio, 0.6 IW/CPE ratio and irrigation at critical growth stages. Application of 60 kg N ha-1 increased all yield attributing characters over application of 30 and 0 kg N ha-1. In case of economics of crop same trend was found and the highest B:C ration was obtained in irrigation scheduling at 1.0 IW/CPE ratio. Whereas, application of 30 kg N ha-1 was recorded highest B:C ration over application of 60 and 0 kg N ha-1. Interaction effect of irrigation and nitrogen levels were found to be non significant in summer season.

Keywords: irrigation regimes, nitrogen levels, summer sesame, agricultural technology

Procedia PDF Downloads 335