Volume 16 (2004)
Table of Contents
Table of Contents
|1.||Kesesuaian Tanah Baki bagi Biodegradasi Sianida (Suitability of Residual Soil for Cyanide Biodegradation)
Mohd Raihan Taha, Nik Norsyahariati Nik Daud & Wan Norita MericanAbstract
A study to assess the suitability of residual soil as a medium for biodegradation processes for cyanide is presented in this paper: The residual soils we obtained from Universiti Kebangsaan Malaysia (UKM) in Bangi (granite residual soil), and Hospital Universiti Kebangsaan Malaysia (HUKM) in Cheras (sedimentary residual soil). The cyanide contaminated soils were bio-treated using the slurry phase or leachate method. Sampels were also mixed with a nutrient solution and innoculated with bacteria that has been breaded in the cyanide contaminated soil. These samples were tested in two environments, i.e.normal nutrient and catalystic (glucose) nutrient. The time allowed for the biodegradation processes was 78 hours. Results showed that HUKM residual soil have.a better characteristics for biodegradation processes compared to UKM residual soil. This is due to greater organic carbon, organic content and acidity of the HUKM residual soil that enhances biodegradation processes.
Perbandingan Proses Penurunan Kromium Heksavalen oleh Ferus Sulfat dalam Medium Berasid dan Beralkali (Comparison of Chromium Hexavalent Reduction Process by Ferrous Sulfate in Medium Acid and Alkaline)
Reduction process followed by precipitation is the most common method used in treating wastewater containing chromium ions. In this study, hexavalent chromium reduction process was carried out in both acidic and alkaline mediums. Ferrous sulphate solution was used as a reducing agent to reduce hexavalent chromium (Cr6+) to trivalent chromium (Cr3+). The reaction in alkaline medium at pH 9.0 was achieved by adding sodium hydroxide solution (NaOH) since chromium wastewater was acidic. During the reaction, the addition of ferrous sulphate solution into reaction medium was monitored through oxidation-reduction potential (ORP) parameter. The results showed that the ORP profiles for the reduction process were different in both acidic and alkaline mediums. When the reduction process was completed in the acidic medium, the absolute ORP value was recorded as 380 mV. The absolute ORP value when the reduction process completed in the alkaline medium was in the range of 0 to –300 mV. The total precipitation in the alkaline medium was 1.6 times higher than acidic medium. For the reduction process in both acidic and alkaline mediums, the rate of reduction process was faster for the higher concentration of Cr6+ion. However, the rate of reduction process in the acidic medium was faster than the alkaline medium because the reduction of Cr6+ concentration was greater in the acidic medium.
Kesan Parameter Pemesinan ke atas Pembentukan Serpihan Semasa Mengisar Hujung Keluli Terkeras AISI H 13 Menggunakan Mata Alat Sermet (Effect of Machining Parameters on Chip Formation During End Milling AISI H13 Steel Using Cermet Tool)
The effect of machining parameters on chip formation during end milling AISI H13 tool steels using cermet inserts was investigated. The machining range were set at speed of 224- 355 m min-1, feed rate of 0.1-0.25 mm tooth-1 and radial depth of cut of 0.3 -0.8 mm. The SEM analysis shows that’ chip formation strongly depends on the depth of cut and feed rate rather than on the cutting speed. At low machining conditions at speed of 224 m min-1 feed rate of 0.1 mm tooth-1 and radial depth of cut of 0.3 mm, discontinuous chip with smooth edges was produced, whereas at high feed rate of 0.25 mm tooth-1 and radial depth of cut of 0.8 mm, saw tooth chips was formed.
Kesan Kehadiran Ion Ferik dalam Pemendakan Hidroksida Logam (Effects of Ferric Ions on Hydroxide Precipitation of Metal Hydroxide)
This research aims to investigate the effects of ferric ions on hydroxide precipitation of copper; zinc, lead, chromium and nickel metals individually as well as in mixed metals. The treatment method used was chemical precipitation using calcium hydroxide as the precipitation agent in the existence of ferric ions as one of the pollutants. The experiment was initially performed with the preparation of synthetic wastewater stocks that were diluted according to the experimental requirements. pH values of the solution were then initially reduced to pH 2 using nitric acid. 50 mL aliquots of sample were obtained at each pH increment and filtered through 0.45 mm porous cellulose nitrate membranes. The procedure was then repeated by adding ferric chloride solutions as a polluting metal. The alkaline medium was found to be the most suitable for metal precipitation purposes since all the optimum pH for all five metals occurred at alkaline medium. The minimum solubility of individual hydroxide precipitation for Cu, Ni, Zn, Pb and Cr were 2.34-5.4 mgL-1, 0-10.78 mgL-1, 1.35- 16.51 mgL-1, 2.34-10.89 mgL-1 and 1.09-5.38 mgL-1 respectively. With the presence of 50 mgL-1 ferric ions, the minimum solubility for Cu, Ni, Zn, Pb and Cr decreased to 2.00-9.44 mgL-1 and 0-4.17 mgL-1 respectively. Hence, the presence of ferric ions was able to effectively increase the metal precipitation as the formation of ferric hydroxide acted as an intermediate kinetic during metal hydroxide precipitation process. The precipitation effect if the presence of ferric ions was more noticeable in mixed metal solutions.
Using Product Platform Architecture for Identification of Part Commonality in Support of Design for Modularity
Modular approach is one of the best design techniques as it promotes better and faster designing process. Due to functional independence and physical similarities, it tends to drive platform development. This paper will discuss the application of modularity approach to drive for platform design from a multi-family home appliances product. By utilising the conventional heuristics rules to identify modules, a platform is then developed so that it can be shared among those products. Three consumer products from different family are used as case study. As a result, a new design is proposed with several improvements to the products in terms of part count and part commonality.
Finite Element Model for Crack Propagation Using Master-Workers Method
This paper describes an algorithm for parallel assembling of the stiffness matrix in simulation of crack propagation in distributed memory environment using masterworkers method. In this algorithm, element stiffness matrix is formed by groups in each processor related by the finite element mesh. Each processor assembles a specific group of elements and no synchronization is required to avoid two or more worker processors sending the calculation result to master processor concurrently. This paper gives the speed-up rate in the simulation of crack propagation. The results indicate excellent
Performance of Packet Filtering Using Back Propagation Algorithm
In this paper we analyzed the use of neural network for packet filtering. The neural network system was designed in eight ways with input to the neural network in the form of either access rules or optimized access rules or binary form of access rules or representing wildcards as 0 & 255 or combination of them. These trained neural networks were analyzed for their correctness and the performance aspects such as training time using test data. In order to further improve the security, the data related to the local usage of the network were also used to train the network. An example of implementing these trained systems in active networks packet filtering was presented.