Cooperation Through Education: How Southern West Bank, Palestine, Can Be Developed Through Agricultural Engineering

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): A. Tamimi. Cooperation Through Education: How Southern West Bank, Palestine, Can Be Developed Through Agricultural Engineering. Vol. IV. September 2002

Influence of Viscosity Modifying Admixture (VMA) on the Properties of SCC Produced Using Locally Supplied Materials in Bahrain

The reluctance in utilizing the advantages of Self Compacting Concrete (SCC) in Bahrain stems from two contributing factors: Lack of research or published data pertaining to locally produced SCC, and a feeling of doubt and uncertainty in the minds of practicing engineers about reliability and suitability of SCC in hardened stage. The primary aim of this study is to explore the influence of viscosity modifying admixtures available in Bahrain on the fresh and hardened properties of SCC. For this purpose, three self-compacting concrete mixes and one control mix were prepared with same water/powder ratio and other ingredients, but with different fluidity. Control mix is considered to compare the strength of SCC with that of the normal concrete. The fluidity was varied by altering the dosage of VMA in different SCC mixes. The filling ability, passing ability and resistance to segregation were evaluated to make sure that prepared mixes satisfy the SCC basic criteria. From each SCC mix and control mix, 9 cubes were cast to obtain compressive strength of SCC in hardened stage after 3, 7 and 28 days of curing. Also, for each SCC mix and control mix, three prisms were cast and their flexural strength was tested after 28 days of curing. The test results of the specimens were used to carry out a comparison of compressive and flexural strength of different mixes of SCC and the control mix. The study shows that SCC prepared using locally supplied materials is also equally reliable as conventional concrete, provided that it satisfies all the basic requirements of SCC in fresh stage and maintains a minimum slump flow of 600 mm

The Potential of Shading Devices for Temperature Reduction in High-Rise Residential Buildings in the Tropics

AbstractThe present study focuses on the effect of shading devices on the indoor temperature of high-rise residential buildings in the hot–humid climate of Malaysia. Several methods can be employed to improve indoor thermal environment, including using a reflective glazing system, using light colors for external surfaces, and using the appropriate thermal properties of external walls and roofs. However, before using any of these methods, it is important to have an optimum shading device to reduce the solar radiation absorption that leads to an overheated indoor environment and an increase in cooling energy loads. Therefore, the main objective of the current paper is to find the extent of a building's solar heat gain and, consequently, the indoor air temperature that is influenced by the external shading devices. A computerized simulation tool (IES<VE>) is used to carry out the investigation, taking Penang as the empirical background of the hot–humid climate. The results indicate that egg-crate shading has a significant impact on decreasing discomfort hours compared with other shading types

Modification of chitin as substrates for chitinase

Enzymes are able to bind to their substrates specifically at the active site. The proximity and orientation of the substrates strongly increase the likelihood that productive E–S complexes will arise. Treated chitin (powder or flake) is more efficient than crystalline chitin. This is because the latter is less active due to its insolubility. The structure of treated chitin is opened; this facilitates its interaction with the enzyme. The purpose of this research was to create a kind of modified chitin and study the characterization of the different types of chitin including functional groups by IR spectrophotometer, pore size, surface area and crystallinity by X-Ray diffraction. Chitin from shrimp shell was modified into colloidal, bead, amorphous and superfine chitin. The results of the IR spectra of colloidal and bead chitin showed a similar pattern with chitin powder; they peaked at 3447 and 3113 cm-1 (OH and NH2 groups), 1645 cm-1 (amide groups N-H) and 1071 cm-1 (group C-O). Superfine and amorphous chitin had similar absorbance with powder chitin but appeared to peak in the fingerprint region. Characterization of physical properties based on the pore size and surface area of powder, colloidal, superfine, amorphous and bead chitin changed the pore radius of each type of chitin due to the treatment of swelling. Crystallinity showed that specific diffractogram pattern in the three main peaks 2q was 9.5, 19.5 and 26 with varying intensity. Chitinase activity assay using modified types of chitin substrate had higher values than chitin powder. The highest activity was in amorphous chitin with values of 1.858 U/mL. This is because it has chitin chain and the rearrangement of its structure was more open, facilitating its interaction with enzyme.Keywords: Chitin modified, chitinase, substrate.Abbreviation: SDS, Sodium dodecyl sulfate; Ct, chitin powder; Cc, colloidal chitin; Sf, superfine; Cb, bead; Ca, amorphous

Modelling the Portevin-Le Chatelier effects in aluminium alloys

Plastic deformation processes are among the most demanding processes in manufacturing causing different microstructure feature in materials. A number of various dislocation patterns can be induced by plastic strain under different conditions. A serrated yielding/jerky flow in some dilute alloys like aluminium-magnesium alloys during plastic deformation is a well-known phenomenon under certain regimes of strain rate and temperature reported in a significant number of works. The serrated features in these materials are so-called the Portevin-Le Chatelier effects. The occurrence of these undesirable effects is due to the interaction between solute atoms and mobile dislocation during the plastic deformation which is known as dynamic strain ageing. There are a significant number of theoretical and numerical investigations that have been focused on describing the serrated behaviour of these materials during plastic deformation. Hence, the fundamental objective of this paper is a general review of different constitutive modelling in regards with this feature. The typical material models and new constitutive models describing this feature are presented. In addition, applications of the models are provided indicating their advantages and disadvantages

Evaluation of FRP concrete compression member under repeated load and harsh environment

Strengthening and rehabilitation have been increasingly applied in many structures to improve their capacity and serviceability. Fiber Reinforced Polymer (FRP) materials are universally known for their ability to improve the load capacity of damaged structural elements because of their high linear-elastic behavior. However, enhancing the capacity of structural elements that are exposed to repeated load coupled with harsh environment is an area that requires further investigation. This research focused on experimental analysis of the behavior and response of confined and unconfined concrete compression members (300mm x 150mm) under repeated load while exposed to 1440 cycles of seawater splash zone in United Arab Emirates (UAE). Confining concrete compression members with Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) sheets have increased the load capacity compared to the control sample at room temperature by 110% and 84%, respectively. Results showed that the average value of compressive strength for the confined concrete exposed to sea water splash zone conditions for CFRP and GFRP specimens has decreased by 33% and 23%, respectively, compared to the confined concrete in the room temperature. However, GFRP specimens showed higher performance in compressive strength under sea water splash zone than those of the CFRP specimens. Different mode of failures such as delamination, de-bonding and combination of such modes were observed and related to various exposure factors and mechanical properties

Photodegradation of 2-naphthol Using Nanocrystalline TiO2

The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ″Degussa P-25″ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved.The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ″Degussa P-25″ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved

Inheritance of Reaction of a Diallel Set of Diploid Alfalfa Clones to Two Pathogens of the Blackstem Complex

In the North Central Region, Phoma herbarum var. medicaginis Rab. And Cercospora zebrine Pass. Cause more damage to alfalfa than other components of the blackstem complex. The objectives of this investigation were: (1) to determine the ecological relationship between the two pathogens, and (2) to obtain some information regarding the genetic systems in alfalfa which condition the reaction to the two fungi. A diallel set was established from eight diploid, heterozygous clones of alfalfa. One P. herbarum and two C. zebrine isolates were used. Three leaves from each plant were excised, placed in a Syracuse watch0glass, sprayed with the inoculum, floated on a 2 percent sugar solution and incubated at 68-72 F in the dark for six days. Since it was difficult to distinguish between the types of lesions produced by each pathogen parasitizing the same tissue, the gross infection was used as a basis to determine the relationship between the two fungi. The magnitude in level of infection produced by the various treatments suggested that the relationship was not neutral, and a certain type of interaction between the two pathogens did exist. Analysis of diallel crosses indicated that dominant and recessive genes in the host plants were involved in controlling resistance to both pathogens. IN addition to dominance, epistatic gene action seemed to play a major role in controlling the reaction of the host plants to both pathogens. Is was concluded that concurrent selection for resistance to both fungi is feasible