Papers by Keyword: Storage

Abstract: Municipal solid waste management continues to be an enormous challenge for developing countries such as Nigeria. With a rapidly increasing population and change in consumption choices in urban cities in Nigeria, the need to cater for and properly manage the increased volume and more diversified waste generated becomes an urgent issue for consideration. Storage and Collection of generated waste make up the crucial elements of waste management systems in any city. Sadly, though, just about a quarter of waste generated in Nigeria is collected. This paper compiles relevant information from recent studies made by researchers and authors on waste management systems in Nigeria to review the current state of the waste storage and waste collection systems in major cities in Nigeria using Lagos and Abuja as case studies. This study also summarizes the methods majorly used for the storage and collection of waste in Nigeria, making recommendations as and when necessary.

Abstract: As a drug product for vitreous replacement, the stability of polydimethylsiloxane (PDMS) during storage is very necessary. PDMS must be stable both chemically and physically during the storage process according to WHO standards. This is necessary to maintain security and regulate the drug supply. Our research shows that low-and medium-viscosity PDMS produced from low-grade octamethylcyclotetrasiloxane (D4) monomer have good stability and storage for 15 months. The optimal time for stability and storage of this PDMS is 5 months. Changes in viscosity values occur due to a very slow chain growth from 5 until 15 months. However, a longer assessment time and other tests are needed to complete the material stability information.

Abstract: Rice is one of the most consumed cereals in the world, and the cultivation of this crop has significant relevance in the southern region of Brazil. When subjected to inadequate conditions of temperature and humidity, rice becomes susceptible to attacks from pests and fungi and, therefore, care in the storage process is of paramount importance, since this is largely responsible for the quality of the harvest. Such care allows the food to arrive without harm to the consumer. In this sense, the mathematical modeling, among numerous possibilities, allows for evaluating the internal temperature of a silo and, through this, taking preventive measures so that the grains maintain their quality. The objective of this work is to model the heat transfer process in a silo prototype containing rice in husk through the explicit finite difference method for a one-dimensional and transient model considering two approaches centered on the spatial derivative: error of order 2 and 4. In addition, the thermal diffusivity of the grain with average value was analyzed. The results obtained by the solutions were analyzed through graphs and statistical indexes comparing with the experimental data of the literature, and the computer simulation was performed through the Google Colab platform. The chosen methodology proved effective for the work, and the predicted temperatures for the approximations of order 2 and 4 denote similarities both graphically and in the precision of the statistical indexes.

Abstract: Recycling and storage of galvanic production sludges requires significant costs and they are strictly regulated by environmental documents. At the same time, the sludges contain a significant amount of non-ferrous metals, including nickel, which are preferable to extract. To evaluate the extracting nickel possibility from the sludges and selecting a method for their processing, it is necessary to study the chemical, phase, fractional material composition.

Abstract: The long-term thermal stability of the drain contacts of three different commercially available SiC MOSFET devices has been determined at a storage temperature of 300 °C. Existing literature suggests that, at this temperature, the nickel silicides associated with ohmic contact creation should be stable, but this was found not to be the case. Our TEM and EDX work revealed silicide phase transformations, further silicide growth and severe thermally-driven degradation of the drain contact metallization stack on top of the silicide layers. We attribute this instability and growth of the silicides to the high storage temperature and large supply of nickel atoms available from the metal stack. The nickel atoms diffuse and decompose the original silicides to enable the formation of a new low temperature Ni₃₂Si₁₂ phase, and slowly decompose the SiC substrate to form additional nickel silicide.

Abstract: Concrete structures exposed to fire suffer from damage, but can remain a certain degree of residual strength. International research has shown that the compressive strength of concrete decreases not only with temperature, but also by the way of cooling and the storage conditions after fire. Fast cooling introduces a thermal shock which, based on experiments by the authors, could result in a 30% additional strength loss with respect to the loss during heating. When storing the concrete after the fire in air or under water, additional strength losses of about 20-30 % are found within 14 days after the fire. In this paper it is investigated for a high performance concrete what the combined effect is of heating, cooling and storage. One of the conclusions – but with respect to the specific test conditions (e.g. slow heating, 550°C max, pre-dried samples) – is that superposing both expected strength losses of about 30% in case a fast cooling is followed by a period of post-cooling storage results in too conservative strength estimations. It is deemed that the cracks resulting from fast cooling, will act as expansion chambers for the newly produced portlandite, thus strongly reducing additional stresses, which results in expected lesser damage.

Abstract: The cause of the degradation was analyzed by applying the highly humid conditions during the storage of cement composed of β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM). For the β-TCP and MCPM stored separately under the humid environment, the mild increase in the setting time was observed, and the product after the setting was entirely dicalcium phosphate dihydrate (CaHPO₄2H₂O: DCPD). However, for the β-TCP and MCPM stored mixed under the same condition, the setting time significantly increased with the period of storage, and the product contained dicalcium phosphate (CaHPO₄: DCP) as major phase, resulting in the loss of setting ability. The formation of DCP could be because of the weak driving force for setting, caused by a feeble supply of water from moisture. As the formation of DCPD requires stronger driving force to overcome the activation barrier, sufficient amount of water is essential. Humid environment during the storage decreased the driving force by the formation of DCP, and the driving force to produce DCPD was lost during the actual setting.

Abstract: Logistics plays an extremely important role in all production and non-production processesin almost every business company. Logistics is a key part of the strategy of each company and none of today's evolving market opportunities may not be used if the supply chain (or logistics) will not work effectively. And effective management of global logistics is certainly not inconsiderable step in the process to the target of each company, which is undoubtedly the maximum profit.

Abstract: The paper deals with the process of assembling which is one of the most important process of store management. Activities related to the assembling and the way of this process organization and realization has significantly impact not only on the accuracy and completeness of consignments but also on the quality of created logistics units. The way of realization of the assembling process is closely associated with its effectivity and with total costs.

Abstract: In the present work a transient numerical model is developed to investigate and predict the performance of a paraffin phase change material (PCM) in the annular portion of the cylindrical container during its solidification and melting processes. Enthalpy method of modeling is adopted and the discretised non-dimensional form of governing equations and boundary conditions are solved by implicit finite difference method by using MATLAB software. The temperature variation of PCM along two axes of the polar co-ordinates (r, z) and the time required for solidification are analyzed and presented. The effect of system variables on the performance of the Latent Heat Thermal Energy system ( LHTES) is studied. The model tested finds application in the concept of free cooling which is the process of storing the coldness of the night time ambient air in the LHTES in order to cool the building during the daytime by retrieving the stored cold energy.