422 research outputs found

    Cadmium biosorption by Rhizopus oligosporus

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    A measure of trade induced adjustment in volume and quality space.

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    In this paper we contribute to the literature on the measurement of international trade flows. Specifically, we combine changes in the volume and quality in matched trade changes to present a simple new index together with a geometric framework that can be used to visualise changes in quality and volume simultaneously. We illustrate the usefulness of our simple extension with data for trade between Malaysia and China between 1994 and 2004

    A Verification Of Periodogram Technique For Harmonic Source Diagnostic Analytic By Using Logistic Regression

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    A harmonic source diagnostic analytic is vital to identify the root causes and type of harmonic source in power system. This paper introduces a verification of periodogram technique to diagnose harmonic sources by using logistic regression classifier. A periodogram gives a correct and accurate classification of harmonic signals. Signature recognition pattern is used to distinguish the harmonic sources accurately by obtaining the distribution of harmonic and interharmonic components and the harmonic contribution changes. This is achieved by using the significant signature recognition of harmonic producing load obtained from the harmonic contribution changes. To verify the performance of the propose method, a logistic regression classifier will analyse the result and give the accuracy and positive rate percentage of the propose method. The adequacy of the proposed methodology is tested and verified on distribution system for several rectifier and inverter-based loads

    Photochemical Thiolation of Carbon Particles with Mercaptoproyltrimethoxysilane

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    Surface modification of carbon black (CB) is an important tool to refashion properties of its composites. CB surface modification is usually practiced through thermal procedures. However, environmental concerns have provided the base to rethink for alternate methods, particularly photochemical methods that are considered comparatively eco-friendly due to reduced chemical and thermal waste. Present investigation is based on a photochemical method for CB surface modification that has effectively modified particle surface with alkoxysilane. This method carries the active centers, generated by photoinitiator, to the shaded areas which otherwise are not possible to reach. Hence, this reaction scheme has prevailed over huge activation barrier without thermal support. A photo-thermal modification method has also been utilized for comparative analysis. Effectiveness of photochemical modification method to alter the surface of CB has been confirmed through different instrumental techniques, including XPS, TGA, FTIR, Raman and SEM

    Effect of Interaction between Bridge Piers on Local Scouring in Cohesive Soils

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    Local scour at the piers is one of the main reasons of bridge foundation undermining. Earlier research studies focused mainly on the scour at a single bridge pier; nevertheless, modern designs of the bridges comprise wide-span and thus group of piers rather than a single pier are usually used to support the superstructure. The flow and scour pattern around group of piers is different from the case of a single pier due to the interaction effect. Reviewing the literature of local scour around bridge piers group revealed that the local scour around bridge piers group founded in cohesive soil bed was not investigated, and most of the scour studies were related to scour in cohesionless soils. The objective of the present study is to investigate the effect of the interaction between two in-line (tandem) circular bridge piers of variable spacings founded in cohesive soil on the local scour. A set of laboratory flume experiments were conducted under the clear-water scour condition to investigate this effect. This study is the first that investigates experimentally the scour around group of bridge piers in cohesive bed. It was found that the maximum scour depth at the upstream pier of the two in-line piers occurred at a spacing of two times the diameter of the pier, scour at the downstream pier was reduced due to a sheltering effect, the interference effect will be reduced for pier spacings larger than three times of the pier diameter. A recent pier scour equation was used to estimate the scour depths at the two in-line piers in cohesive soil and compare the estimated value with the measured scour depths in the laboratory. The comparison indicated that the proposed scour equation overestimates the scour depths at both the upstream and the downstream pier

    Students’ Perceptions and Challenges in the Use of Small Group Discussion in English-Speaking Class Activities

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    Small Group Discussion (SGD) is one of the techniques that can be used in learning and teaching English speaking skills. This study aims to find out students' perceptions and the challenges students encountered when using SGD in their English-speaking activities at SMK Dirgantara Putra Bangsa. This study used mixed method approaches, and the instruments used in collecting data were questionnaires and semi-structured interviews. Respondents in this study were 23 students (7 males and 16 females) from class X of SMK Dirgantara Putra Bangsa in the academic year 2023–2024 and through a purposive random sampling technique. Furthermore, a questionnaire was used to figure out students' perceptions, and semi-structured interviews were conducted to find out the challenges encountered by students when using SGD. Six respondents (5 females and 1 male) were selected in the interview session based on their scores, they are; two students with the highest scores, two students with middle scores, and two students with low scores to be interviewed. The semi-structured interview data were analyzed qualitatively using the interactive model proposed by Miles & Huberman (1994). The results of this study show that students' perceptions of using SGD can enhance their speaking skills. Meanwhile, the results of the interviews indicated that lack of vocabulary and self-confidence were challenges those students encountered in using SGD. This learning model may help students participate, engage, and enhance their confidence in speaking English, and teachers are aware of the importance of choosing the right learning model to achieve successful learning in the classroom are a few pedagogical implications of the present study

    Evaluation of Novel Bio-friendly Two-step Process in the Removal of Heavy Metals from the Wastewater

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    Two-step treatment technique was developed for the treatment of water by Pseudomonas aeroginosa in a bioreactor in a first phase and then the bacterial treated water was treated with the vetiver grass, cattails and water hyacinth in second phase. Two-step process of bioremediation of 13 days was found to be satisfactory for As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn in compared to the direct treatments with vetiver grass, cattails and water hyacinth in 20 days. As the plants cannot work or tolerate the higher concentrations of heavy metals, so with the first step on an average 52.48% reduction of heavy metals were done within 5 days. It was observed that 100% removal of Pb was found by two-step process of Pseudomas aeroginosa with cattails and water hyacinth, respectively in 13 days, while 98.16% removal of Pb was found by direct plant treatment of water hyacinth in 20 days. It was clear that the two-step treatment for vetiver grass, cattails and water hyacinth were found as the most effective treatments

    Allelopathic Potential of Rice Varieties against Spinach (Spinacia oleracea)

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    Two laboratory experiments were conducted to investigate the allelopathic effects of rice varieties on spinach (Spinacia aleracea L.). Fifteen rice varieties were included for evaluation. Two methods viz. Sandwich method and Relay seeding method were used to observe the allelopathic effects of rice varieties on seed germination, mean germination time, shoot and root length and dry matter production of spinach as a test crop. Average inhibition in spinach growth was calculated to evaluate the allelopathic potential of the rice varieties. All the selected varieties of rice were more or less detrimental to studied characters of spinach. WITA12 resulted in about 48% average percent inhibition of spinach growth. On the basis of average percent inhibition rice varieties ranked in order of WITA12>Dular>WITA3>BR26>BRRI dhan42>BRRI dhan39>BRRI dhan31>BRRI dhan44>BRRI dhan40>BR19>BRRI dhan43>BRRI dhan46>BRRI dhan47>BRRI dhan45>BRRI dhan28. Both the evaluation methods were positively correlated in determining percent reduction in most of the parameters of spinach due to allelopathic effects of rice

    RESPON VARIETAS PADI IR64 DAN IR64-SUB 1 TERHADAP PERENDAMAN DAN PEMUPUKAN N

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    There are many new rice varieties have been produced, introduced and breed at IRRI and the other National Agriculture Research Institutes that are tolerance to submergence condition to anticipate global warming and flash flooding around theworld. Among others are IR64-Sub 1, Suwarna-Sub 1, Inpara-1, Inpara-2, inpara-3 etc. However, those new varieties have not been tested widely yet, and the method of rice cultivation under submergence condition have not been adjusted, including the nutrient management.A greenhouse experiment was conducted at Muara Research Station, Bogor during 2008 dry season. The objectives of this experiment are (1) to study the effects of time of submergence and N application on plant growth and yield of  R64 and IR64-Sub 1 rice varieties; (2) to find the best nutrient management for submergence rice varieties. The experiment was conducted during 2008 dry season at greenhouse, Muara Research station, Bogor. The design of the  experiment was a Completely Randomized Factorial Design with three eplications. Factor 1 is rice variety (IR64 and IR64-Sub 1); Factor 2 is time of submergence (without submergence or control, submergence at vegetative phase (15 to 25 d.a.t), and at generative phase (35 to 45 d.a.t)). Factor 3 is N application, namely (F1) 300 kg Urea/ha 3x applications at 7 d.a.t- 30 d.a.t – 55 d.a.t; (F2) Mudball urea –300 kg Urea/ha applied once at 7 d.a.t. (F3) compost; and (F4) compost and urea; (F5) Urea and silikat.urea-N application at four time 0 d.a.t – 7 d.a.t – 30 d.a.t – 55 d.a.t (factor C). The results of experiments showed that submergence changes rice plant growth pattern (mainly tiller number and plant height), increased dry grain weight of IR64, namely 35.9 g at early vegetatif phase and 29.9 g at late vegetatif phase, while for IR64-Sub 1 32.6 g and 30.3 g at the same respective phase. Mudball urea and silicate application improved plant resistant to submergence and increase rice yield

    Economic integration and the evolution of trade: a geometric interpretation of trade measures

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    The increase in global trade and the ongoing erosion of trade barriers makes the analysis of trade patterns one of the key areas in international economics. Much of the post-war expansion of trade took the form of intra-industry trade (IIT). This paper presents a simple geometric tool to analyse trade patterns specifically inter and intra-industry trade and the compatibility between levels and measures of IIT. The applicability our methodology is demonstrated using the UKs trade experience during the critical period of EU integration 1988-1997
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