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Fouling studies on hydrophobic PVDF-bentonite hollow fiber membrane during membrane distillation of palm oil mill effluent
No full textMembrane distillation (MD) is one of the emerging methods that can be adopted for oily wastewater treatment. However, the problems associated with membrane surface fouling may impede its separation efficiency. In this work, we performed a fouling study using self-synthesized polyvinylidene difluoride (PVDF)-bentonite hollow fiber membrane (HFM) to treat palm oil mill effluent (POME) via direct contact membrane distillation (DCMD). To date, there is no report on POME treatment using MD technology based on PVDF-bentonite HFM. The fouling tendency was identified based on the membrane's permeate flux and pollutant rejection. The fouled membranes after POME treatment were characterized based on its morphology, functional group, water contact angle, surface roughness and mechanical strength. The results showed that the average permeate flux of MD was 3.34 kg/m2·h over 72-h operation. The membrane showed good performance in separating pollutants with >95 % removal rate recorded for chemical oxygen demand, nitrate nitrogen, total suspended solid, total dissolved solid, color and turbidity. However, based on the post-characterization analysis, the used membranes still suffered from fouling after 72-h DCMD test. Thus, an in-depth investigation into the prevention and control of membrane fouling is still necessary for the POME treatment using DCMD
Perfect codes in induced subgraph of unit graph associated with some commutative rings
No full textThe unit graph associated with a ring R is the graph whose vertices are elements of R , and two different vertices x and y are adjacent if and only if x +y∈U R where U(R) is the set of unit elements of .R The aim of this paper is to present the perfect codes in induced subgraph of unit graph associated with some commutative rings with unity in which its vertex set is U(R). UR We characterize some families of commutative rings with induced subgraphs of unit graphs accepting the non-trivial perfect codes, and some other families of commutative rings with induced subgraphs of unit graphs which do not accept perfect codes
A mini-review of recent studies on lead and lead-free perovskite materials for solar cells application and their issues
Get PDFPerovskite is gaining popularity in solar cell technologies and optoelectronics that rely on lead-based material. Perovskite solar cell (PSC) technologies are viewed as promising forthcoming innovations for their proficiency and monetary of the thin film due to high demand in the technology market. Lead-free perovskite material has become a viable alternative to lead-based perovskite, which has dominated the solar cell market for many years, due to toxicity and stability difficulties that have plagued lead-based solar cells. The large-scale commercial manufacture of lead-free halide perovskites solar cells can be expanded and its benefits in the solar field could be enhanced. Compared with lead-based perovskite, the lead-free perovskite material could also achieve a high-power conversion efficiency (PCE) indicating good solar cell performance. This review studied the perovskite materials, challenge of lead perovskite solar cell commercialization and summarizes recent research work regarding the perovskite solar cell. Moreover, this review forecast the future of perovskite solar cells in parallel with the Third Generation of Solar Cells
Imperialist competitive algorithm for increasing the lifetime of wireless sensor network
Get PDFRecent years have seen the rapid growth in the applications of wireless sensor network (WSN) which is due to the advances of sensor nodes with low cost and tiny size. Despite the various potential applications of WSN, one of the key tasks in sensor network design is to make sure that the network is functional as long as possible. This paper presents an energy-efficient cluster head selection algorithm for the clustering of heterogeneous WSN, inspired by Imperialist Competitive Algorithm (ICA). In order to reduce the network energy consumption and subsequently increases the sensor network lifetime, the clustering problem is transformed into an optimization problem and the specific cost function is used to select the cluster heads in a way that the energy utilization of the network is optimized. Extensive simulation works are done based on MATLAB to test the algorithm in various network scenarios, with different network sizes and number of nodes. Simulation results have shown that the proposed algorithm is able to extend the network lifetime compared to its comparative by up to 154 percent in terms of first node death. Furthermore, choosing the optimum set of cluster heads at every round has proved that our proposed algorithm not only could reduce the network energy consumption, but also improves the total data delivery at the base station up to 59 percent compared to the well-known algorithm
Effect of heat treatment on microhardness of electroless Ni-YSZ cermet coating
No full textPurpose: The paper discussed the effect of heat treatment on electroless nickel-yttria-stabilised zirconia (Ni-YSZ) cermet coating. Ni-YSZ cermet coating has potential applications such as cutting tools, thermal barriers, solid oxide fuel anode, and various others. The compatibility of ceramic YSZ and metallic nickel in terms of the mechanical properties such as hardness by varying the heating temperature, time and ceramic particle size is highlighted. Design/methodology/approach: Ni-YSZ cermet coating was deposited onto a highspeed steel substrate using the electroless nickel co-deposition method. The temperature and time were varied in a range of 300-400°C and 1-2 hours, respectively. The microhardness measurements were carried out using a Vickers microhardness tester (Shimadzu) according to ISO 6507-4. The surface characterisation of the cermet coating was carried out using JOEL Scanning Electron Microscope (SEM) coupled with Energy Dispersive X-ray (EDX) JSM 7800F. The crystallographic structure of materials was analysed by X-ray diffraction (XRD) Bruker D8 Advance instrument. Findings: It was found that the microhardness of Ni-YSZ cermet coating with the ratio of 70:30, respectively, is directly proportional to the heating temperature and time. Heating the Ni-YSZ cermet coating at 300°C from room temperature (rtp) to 1 hour shows a 12% microhardness increment, while from 1 to 2 hours gives a 19% increment. Compared to heating at 350°C and 400°C, the increment is more significant at 33% and 49% for rtp to 1 hour and 8% and 16% for 1 to 2 hours, respectively. In addition, the effect of varying YSZ particle size in the Ni-YSZ cermet gave response differently for heating temperature and heating time. Research limitations/implications: The paper is only limited to the discussion of the heat treatment effect on Ni-YSZ cermet coating hardness property. The tribological effect will be in future work. Practical implications: The microhardness data may vary due to the Vickers microhardness force applied and the amount of ceramic particle incorporation and phosphorus content in the nickel matrix. Originality/value: The value of this work is the compatibility of the ceramic YSZ and metallic nickel matrix in terms of mechanical properties, such as hardness, upon heat treatment
Simulation and analysis of voltage and electric field distribution along high voltage insulator
No full textHigh voltage insulators play a major rule in energy transmission systems. The main role of these insulators is to ensure and maintain high level of line-tower insulation. However, the voltage distribution of insulator string is uneven which may easily lead to corona, insulators’ surface deterioration and even flashover. Although there is various research for this topic, but there still have some limitations regarding on the performance of insulator in terms of voltage and electric field distributions. In this project, high voltage insulator strings with will be designed and simulated by using simulation software such as SOLIDWORKS and EMS software and their data (electric field and voltage distributions) will be collected and analysed. The modelling of the insulator will be designed by considering the effect of conductor and transmission tower as well as different material type of high voltage insulator such as porcelain, glass and silicon rubber. In addition, the improvement on the performance of the insulator also will be taken into consideration in this project. The research described in this dissertation is directly applicable to the Voltage and Electric Field distributions along the high voltage insulators design and development
Recent progress on low-cost ceramic membrane for water and wastewater treatment
No full textGreat progress in the development of low-cost ceramic membranes from alternative materials have been achieved recently towards various application especially water and wastewater treatment. However, their significance has not been fully recognized and understood especially in term of their microstructural analysis such as formation of grain growth and microcracks. This review paper summarizes fabrication method, alternative materials, microstructure, wettability, mechanical properties and application of low-cost ceramic membrane. The fabrication method including slip casting, tape casting, extrusion, pressing method and phase inversion technique are described. Alternative materials used in low-cost ceramic membrane fabrication are discussed and categorized into clays, agricultural waste, industrial waste and animal bone waste. The mechanisms of morphology formation, microstructure and wettability properties are analysed. Modification strategies for the surface of low-cost ceramic membrane are discussed, and classified into modification for separation application, modification for photocatalytic application and modification for membrane distillation and membrane contactor system. Modification improves the membrane structure by changing the pore size, porosity and wettability properties of low-cost ceramic membranes. Mechanical properties of low-cost ceramic membranes are also discussed in detail towards several mechanism, like grain growth phenomenon and formation of microcracks which also considered as membrane defects. Grain growth phenomenon can be divided into normal and abnormal grain growth. Meanwhile, formation of microcracks could be occurred in single-phase polycrystalline ceramics that have anisotropic grains or biphasic polycrystalline grains. The application of low-cost ceramic membrane in seawater desalination, oily wastewater treatment, heavy metal adsorption, textile separation and photocatalytic application are reviewed. Finally, some possible opportunities and challenges for further development of low-cost ceramic membrane are pointed out
Experimental study on the performance of one-directional and bi-directional flow conditions across in-line tube banks heat exchanger
No full textThe one-directional flow condition and the bi-directional flow condition are two flow conditions that can be found in many energy systems depending on the nature of the flow and the working mechanism of the system. This paper reports the differences in heat transfer performance for an in-line tube banks heat exchanger that is placed in the one-directional and the bi-directional flow conditions. The experiments involve the use of a blower as a flow inducer for one-directional flow while a loudspeaker with a constant frequency of 14.2 Hz is used as a flow inducer for bi-directional flow condition. A quarter wavelength resonator with 4 mm wall thickness and a length of 6600 mm was used in the investigation. The results of velocity and temperature were recorded using a hotwire anemometer and a type-K thermocouple, respectively. Results show that the behaviour of velocity and temperature in one-directional and the bi-directional flow conditions over an in-line heated tube banks are different with a maximum difference of 52 % for velocity and 79 % for temperature
Pre-trained language model with feature reduction and no fine-tuning
No full textPre-trained language models were proven to achieve excellent results in Natural Language Processing tasks such as Sentiment Analysis. However, the number of sentence embeddings from the base model of Bidirectional Encoder from Transformer (BERT) is 768 for a sentence, and there will be more than millions of unique numbers when the dataset is huge, leading to the increasing complexity of the system. Thus, this paper presents the feature reduction of the sentence embeddings classification with BERT to decrease the number of features and complexity by using feature reduction algorithm. With 50% fewer features, the experimental results show that the proposed system improves the accuracy by 1%−2% with 89% lesser GPU memory usage
Speed up grid-search for Kernels selection of support vector regression
No full textThe aerobic granular sludge (AGS) is a one of the promising technologies for wastewater treatment. In this paper, several modelling strategies are developed to predict the behaviour of AGS. The modelling approaches are cautiously chosen to address the complex dynamic of AGS due internal interactions between the sludge characteristics and variables. Since only a small dataset is available, the support vector regression (SVR) method is employed. Instead of using the time-consuming and trial-and-error or grid search methods to determine the pair of kernels, the particle swarm optimization (PSO) and genetic algorithm (GA) techniques are proposed. Using a dataset generated from an AGS process in sequential batch reactor at a working temperature 30 ˚C, the SVR-PSO, SVR-GA and SVR-Grid Search predict models are developed and compared. The results show that the proposed SVR-PSO and SVR-GA models improve the prediction accuracy of chemical oxygen demand (COD) by 10% as compared to the conventional SVR-Grid Search model. The computational time also was reduced up to 86% and 79% respectively