Numerical analysis of deformation and stability in the formation for railway tracks

Over the past few decades, the increasing demands of railways operations in the form of heavy loading and high speed have been noticed. Railway formation and ballast deform progressive under heavy axle cyclic loading, therefore the rail track needs proper design of ballast and formation bed to achieve the desire stiffness and stability for the safe and sound serviceability of the track. For the overall stability of the track on soft formation, the ground is improved by different techniques prior to the construction on that, in order to avoid the failure and differential settlement during the designed trains operation. The numerical analyses illustrate that the total deformation and bearing capacity of the railway tracks mostly depend on the changes in the friction angle and cohesion of the selected soils of the subgrade. To avoid failure in the formation of track under the design loads, the proper selection of types of soils, its layer thickness, well compaction during construction and provision of proper track drainage system are extremely important. For the construction of new railway tracks the soils having greater values of friction angle, cohesion and elastic stiffness with the well graded ballast cushion under the sleepers of designed side slopes can be used to reduce the maintenance cost, considerably increase the life time of the components of the tracks and ultimately give better performance of the tracks

Improvement of Strength and Permeability Attributes of Silty Sand Type of Soils using Enzyme Induced Calcite Precipitation

ABSTRACT Enzyme Induced Calcite Precipitation (EICP) is one of the soil stabilization techniques based on microbiological activity. In this technique, urea decomposes with the aid of urease enzymes in the presence of calcium chloride and produces calcite, which acts as a bio-clogging and bio-cementing material. In this study, test tube experiments are performed to assess the optimal amount of calcium chloride, urea, and urease enzymes to be used for engineering applications. The silty sand type of soil is treated with different proportions namely; P1 (0.1g urease enzymes, 0.375g urea, 0.9g CaCl2), P2 (0.2g urease enzymes, 0.75g urea, 1.8g CaCl2), and P3 (0.4g urease enzymes, 1.5g urea, 3.6g CaCl2), to analyze their effect on strength and permeability attributes of soils after 14 days of curing time. It was observed that an increase in EICP content causes a substantial increase in shear strength particularly cohesion due to the bio-clogging phenomenon induced in soil particles by EICP which eventually leads to a decrease in permeability and inhibits the activity of urease. Overall, P3 yields higher cohesion (48 kPa) than P1(40 kPa), P2 (43kPa), and untreated soil samples (31 kPa). Furthermore, P3 causes a significant decrease in permeability as compared to P2, P1, and untreated soil samples tested after 14 days of the curing period. The findings of the study suggest the successful implementation of EICP for soil stabilization. Key Words: Enzyme Induced Calcite Precipitation (EICP); permeability; shear strength; bio-clogging; bio-cementation

MATHEMATICAL MODELLING FOR MAGNETITE (CRUDE) REMOVAL FROM PRIMARY HEAT TRANSFER LOOP BY ION-EXCHANGE RESINS

The present research focuses to develop mathematical model for the removal of iron (magnetite) by ion-exchange resin from primary heat transfer loop of process industries. This mathematical model is based on operating capacities (that's provide more effective design as compared to loading capacity) from static laboratory tests. Results showed non-steady state distribution of external Fe2+ and limitations imposed on operating conditions, these conditions includes; loading and elution cycle time, flow rate, concentration of both loading and removal, volume of resin required. Number of generalized assumptions was made under shortcut modeling techniques to overcome the gap of theoretical and actual process design. KEY WORDS: Magnetite, Mathematical modeling, Ion-exchange resin, Operating capacity, Loading capacity Bull. Chem. Soc. Ethiop. 2009, 23(1), 129-133

Self-Organized Disjoint Service Placement in Future Mobile Communication Networks

Future mobile communication networks will offer many ubiquitous services to its clients such as voice and video communication, access to data and files, use of virtual resources in cloud, etc. The provision of these services will have to face the different challenges posed by future wireless networks such as changing network topology, variable load conditions, clients’ distribution, QoS requirements etc. is a very difficult task and requires a high degree of self-organization in network operations. One important problem in this context is the self-organized service placement which refers to the problem of finding optimal nodes in the network that are most suitable for hosting a particular service type. An optimal placement of a service and its instances (replicas) not only minimizes the service costs but also reduces the overall network traffic and improves connectivity between clients and servers. This paper proposes a novel network service called Self-Organized Disjoint Service Placement (SO-DSP) service which manages other network services and their instances in order to achieve overall network optimization while keeping the individual service’s quality at the same level for its clients. The clients of SO-DSP are not the end-users of the network but the offered network service

Selective transportation of molybdenum from model and ore through poly inclusion membrane

The extraction of molybdenum from the aqueous solution through poly inclusion membrane (PIM) containing tri-caprylylmethylammonium chloride (Aliquat-336) as a carrier has been investigated. A solution of molybdenum in phosphoric acid was used as a feed side while sodium hydroxide was used as stripping reagent. The results indicate that maximum flux value was obtained at 0.16 M Aliquat-336. Increase in H3PO4 concentration from 0.05 to 1.5 M results into an increase in molybdenum ions. The maximum flux of 3.00×10−6 mol/m2s through PIM was found at 1.5 M H3PO4. The optimized conditions were applied for removal of Mo(VI) from ore and more than 97 % Mo(VI) was extracted.   Bull. Chem. Soc. Ethiop. 2020, 34(1), 93-104. DOI: https://dx.doi.org/10.4314/bcse.v34i1.

Research Article Software Component Selection Based on Quality Criteria Using the Analytic Network Process

Component based software development (CBSD) endeavors to deliver cost-effective and quality software systems through the selection and integration of commercially available software components. CBSD emphasizes the design and development of software systems using preexisting components. Software component reusability is an indispensable part of component based software development life cycle (CBSDLC),which consumes a significant amount of organization’s resources, that is, time and effort. It is convenient in component based software system (CBSS) to select the most suitable and appropriate software components that provide all the required functionalities. Selecting the most appropriate components is crucial for the success of the entire system. However, decisions regarding software component reusability are often made in an ad hoc manner, which ultimately results in schedule delay and lowers the entire quality system. In this paper, we have discussed the analytic network process (ANP) method for software component selection. The methodology is explained and assessed using a real life case study

Green synthesis of silver nanoclusters via Melia azedarach plant and their potential towards catalytic reduction of 4-nitrophenol

Biomolecules present in the plant extracts have potential to reduce metal ions to nanoclusters by a single-step green synthesis approach. In the current study, we have synthesized the silver nanoclusters (AgNCs) from a medicinal plant, Melia azedarach and studied their catalytic activity toward the reduction of 4-nitophenol to 4-aminophenol and organic dyes. Morover, the phytochemical analysis of the plant extract was carried out in order to determine the bioactive compounds present in it. Metallic nature of the synthesized AgNCs was verified by X-ray diffraction study, while their morphology and size of was confirmed by transmission electron microscopy and Zetasizer, respectively. The study revealed that they were 56±2 nm in size and formed clusters. Fourier transformed infrared spectroscopy gives information about the different functional groups present in synthesized these NCs. Furthermore, the important catalytic applications, such as catalytic reduction of 4-nitrophenol in the presence of mild reducing agent NaBH4 and the catalytic degradation of organic dyes was monitored by FTIR. Therefore, these results indicate that the obtained nanomaterials have important applications in industrial areas.                     KEY WORDS: Green synthesis, Silver nanoclusters, Catalytic reduction, Characterization   Bull. Chem. Soc. Ethiop. 2021, 35(1), 197-206. DOI: https://dx.doi.org/10.4314/bcse.v35i1.1

E-Health System: A Study of Components and Practices in Developing Countries

E-health systems used in different health setups are rare in developing countries but they consist of the computerization of patient records in hospitals and clinics, document delivery through Internet, information exchange and communication, e-Cards for patient ID, electronic scheduling system, hospital labs and hospital admission, computerized diagnosis and support for treatment. It also provides advanced decision-making and sophisticated use of diagnostic laboratories. Every e-health system establishes a basic ‘infrastructure’ of computers, networks, communications and a technical department filled with IT professionals to continuously uphold and improve the infrastructure, give training to  the doctors & physicians and other medical staff and continuously provide technical support as and when required by them. Given the uncontrollable nature of technical support for e-health systems, developing countries like Pakistan are facing issues in creating full-bodied infrastructural facilities that are both competitive with the external environment and compatible with the internal user requirements. This piece of writing is an effort to highlight some of the main issues in developing countries in connection with adoption and use of e-health systems. Also this study intends to identify some of the prospects for IT-applications in healthcare organizations in countries like Pakistan just for the reduction of their sense of isolation in the world by connecting the doctors’ community online through internet facilities to learn, and do business and carry out organizational processes effectively. Keywords: ICTs, E-health systems, components (e-health) and practices (e-health)