Thermal performance of residential house using interlocking compressed earth brick (ICEB) as an alternative wall material

Buildings are usually designed and constructed without the concern of its impact to the environment and human comfort. Most contributes to poor thermal performance and high energy consumption. Over the years, in Malaysia, there has been an increasing interest in the use of interlocking compressed earth bricks (ICEB) - formed from stabilized earth - for masonry buildings. Due to its green characters and economical benefits, ICEB has gained wide recognition for use in the construction of building envelope systems. Since little information is available on the thermal performance characteristics of ICEB, a laboratory testing and simulation analysis was done to investigate its thermal insulation characteristics and to look at its thermal performance when applied as wall material for a residential building. Thermal properties of ICEB (k-value, R-value and U-value) were obtained by using Guarded Hot Plate Laboratory Testing. Field measurement of a sample house with fired clay brick as the wall material was undertaken over three consecutive days to confirm the existence of thermal comfort problems. Indoor environmental parameters measured include air temperature, mean radiant temperature and relative humidity; while the measured outdoor environmental parameters were air temperature and relative humidity. Thermal simulation of a sample house was done by using ECOTECT Software and results attained were compared with field measurements data for verification. For purpose of parametric study, the wall of the model was replaced with ICEB brick. This is to determine the effect of using the brick as compared to the common brick used in the real house. It has been found from the simulation that ICEB performed better thermally as compared to fired clay brick particularly during the daytime; however, due to the high thermal mass of ICEB, more heat will be released into the indoor spaces at night time. Nevertheless, the night time indoor temperature due to ICEB is still within the comfort range. It also showed that spaces with larger areas of enclosures made of materials with high k-value such as glass window and sliding door will have slightly higher indoor air temperature

Penghasilan panduan keselamatan industri bagi kegunaan bakal graduan Kejuruteraan Elektrik Politeknik

Panduan keselamatan industri merupakan satu bentuk bimbingan yang penting kepada pelajar supaya mereka dapat mengetahui dengan jelas tentang amalan dan pengurusan keselamatan keija. Dengan adanya kesedaran dan pengetahuan yang jelas tentang keselamatan keija maka sudah tentu matlamat kemalangan sifar akan mudah tercapai. Untuk perkara ini, satu penyelidikan telah dijalankan untuk menguji tahap pengetahuan pelajar tentang keselamatan industri bagi tujuan untuk menghasilkan sebuah panduan keselamatan industri. Panduan yang telah dihasilkan ini, telah dibuat penilaian mengenai isi kandungan , kebolehlaksanaan dan mesra pengguna kepada pelajar Diploma Kejuruteraan Elektrik di Polileknik Sultan Abdul Halim Muadzam Shah, Jitra, Kedah. Instrumen yang digunakan dalam kajian ini adalah soal selidik. Hasil analisis kajian menunjukkan bahawa nilai purata yang diperolehi daripada penilaian terhadap tahap pengetahuan pelajar adalah sederhana rendah manakala isi kandungan, kebolehlaksanaan dan mesra pengguna pula telah menunjukkan kadar setuju yang agak tinggi. Oleh itu sebagai rumusannya didapati bahawa panduan keselamatan industri yang dihasilkan ini boleh diterima pakai dan boleh membantu meningkatkan pengetahuan pelajar dalam pembelajarannya. Adalah diharapkan agar penyelidikan lanjutan dapat dilakukan terhadap panduan keselamatan industri ini agar ianya dapat dihasilkan kedalam bentuk yang lebih berkesan penggunaannya

Real-time power system dynamic security assessment based on advanced feature selection for decision tree classifiers

This paper proposed a novel algorithm based on advanced feature selection technique for decision tree (DT) classifier to assess the dynamic security in power system. The proposed methodology utilized symmetrical uncertainty (SU) to reduce the data redundancy in a dataset for DT classifier based dynamic security assessment (DSA) tools. The results show that SU reduces the dimension of the dataset used for DSA significantly. Subsequently, the approach improves the performance of DT classifier. The effectiveness of the proposed technique is demonstrated on modified IEEE 30-bus test system model. The results show that the DT classifier with SU outperform the DT classifier without SU. The performance of the proposed algorithm indicates that the DT classifier with SU is able to assess the dynamic security of the system in near real-time. Therefore, it is able to provide vital information for protection and control application in power system operation

Efficient Spectral Domain MoM for the Design of Circularly Polarized Reflectarray Antennas Made of Split Rings

The method of moments (MoM) in the spectral domain is used for the analysis of the scattering of a plane wave by a multilayered periodic structure containing conducting concentric split rings in the unit cell. Basis functions accounting for edge singularities are used in the approximation of the current density on the split rings, which makes it possible a fast convergence of MoM with respect to the number of basis functions. Since the 2-D Fourier transforms of the basis functions cannot be obtained in closed-form, judicious tricks (controlled truncation of infinite summations, interpolations, etc.) are used for the efficient numerical determination of these Fourier transforms. The implemented spectral domain MoM software has been used in the design of a circularly polarized reflectarray antenna based on split rings under the local periodicity condition. The antenna has been analyzed with our spectral domain MoM software, with CST and with HFSS, and good agreement has been found among all sets of results. Our software has proven to be around 27 times faster than CST and HFSS

Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities

Recently there has been a flurry of research on the use of reconfigurable intelligent surfaces (RIS) in wireless networks to create smart radio environments. In a smart radio environment, surfaces are capable of manipulating the propagation of incident electromagnetic waves in a programmable manner to actively alter the channel realization, which turns the wireless channel into a controllable system block that can be optimized to improve overall system performance. In this article, we provide a tutorial overview of reconfigurable intelligent surfaces (RIS) for wireless communications. We describe the working principles of reconfigurable intelligent surfaces (RIS) and elaborate on different candidate implementations using metasurfaces and reflectarrays. We discuss the channel models suitable for both implementations and examine the feasibility of obtaining accurate channel estimates. Furthermore, we discuss the aspects that differentiate RIS optimization from precoding for traditional MIMO arrays highlighting both the arising challenges and the potential opportunities associated with this emerging technology. Finally, we present numerical results to illustrate the power of an RIS in shaping the key properties of a MIMO channel.Comment: to appear in the IEEE Transactions on Cognitive Communications and Networking (TCCN

Unfermented Freeze-Dried Leaf Extract of Tongkat Ali (Eurycoma longifolia Jack.) Induced Cytotoxicity and Apoptosis in MDA-MB-231 and MCF-7 Breast Cancer Cell Lines

possible anticancer mechanism of action against breast cancer cell lines: non-hormone-dependent MDA-MB-231 and hormonedependent MCF-7. -e leaves of E. longifolia were processed into unfermented and fermented batches before drying using freeze and microwave-oven drying techniques. Obtained extracts were tested for cytotoxicity effect using MTT assay and phenolic determination using HPLC-DAD technique. -e most toxic sample was analyzed for its apoptotic cell quantification, cell cycle distribution, and the expression of caspases and apoptotic protein using flow cytometry technique. Fragmentation of DNA was tested using an agarose gel electrophoresis system. -e results determined that the unfermented freeze-dried leaf extract was the most toxic towards MDA-MB-231 and MCF-7 cells, in a dose-dependent manner. -is extract contains the highest phenolics of gallic acid, chlorogenic acid, ECG, and EGCG. -e DNA fragmentation was observed in both cell lines, where cell cycle was arrested at the G2/M phase in MCF-7 cells and S phase in MDA-MB-231 cells. -e number of apoptotic cells for MDA-MB-231 was increased when the treatment was prolonged from 24 h to 48 h but slightly decreased at 72 h, whereas apoptosis in MCF-7 cells occurred in a time-dependent manner. -ere were significant activities of cytochrome c, caspase-3, Bax, and Bcl-2 apoptotic protein in MDA-MB-231 cells, whereas MCF-7 cells showed significant activities for caspase-8, cytochrome c, Bax, p53, and Bcl-2 apoptotic protein. -ese results indicate the ability of unfermented freeze-dried leaf extract of E. longifolia to induce apoptosis cell death on MDA-MB-231 and MCF-7, as well as real evidence on sample preparation effect towards its cytotoxicity level

A Novel Design Approach to X-Band Minkowski Reflectarray Antennas using the Full-Wave EM Simulation-based Complete Neural Model with a Hybrid GA-NM Algorithm

In this work, a novel multi-objective design optimization procedure is presented for the Minkowski Reflectarray RAs using a complete 3-D CST Microwave Studio MWS-based Multilayer Perceptron Neural Network MLP NN model including the substrate constant εr with a hybrid Genetic GA and Nelder-Mead NM algorithm. The MLP NN model provides an accurate and fast model and establishes the reflection phase of a unit Minkowski RA element as a continuous function within the input domain including the substrate 1 ≤ εr ≤ 6; 0.5mm ≤ h ≤ 3mm in the frequency between 8GHz ≤ f ≤ 12GHz. This design procedure enables a designer to obtain not only the most optimum Minkowski RA design all throughout the X- band, at the same time the optimum Minkowski RAs on the selected substrates. Moreover a design of a fully optimized X-band 15×15 Minkowski RA antenna is given as a worked example with together the tolerance analysis and its performance is also compared with those of the optimized RAs on the selected traditional substrates. Finally it may be concluded that the presented robust and systematic multi-objective design procedure is conveniently applied to the Microstrip Reflectarray RAs constructed from the advanced patches

Improved thresholding and quantization techniques for image compression

In recent decades, digital images have become increasingly important. With many modern applications use image graphics extensively, it tends to burden both the storage and transmission process. Despite the technological advances in storage and transmission, the demands placed on storage and bandwidth capacities still exceeded its availability. Moreover, the compression process involves eliminating some data that degrades the image quality. Therefore, to overcome this problem, an improved thresholding and quantization techniques for image compression is proposed. Firstly, the generated wavelet coefficients obtained from the Discrete Wavelet Transform (DWT) process are thresholded by the proposed Standard Deviation-Based Wavelet Coefficients Threshold Estimation Algorithm. The proposed algorithm estimates the best threshold value at each detail subbands. This algorithm exploits the huge number of near-zero coefficients exist in detail subbands. For different images, the distribution of wavelet coefficients at each subband are substantially different. So, by calculating the standard deviation value of each subband, a better threshold value can be obtained. Next, the retained wavelet coefficients are subjected to the next proposed Minimizing Median Quantization Error Algorithm. The proposed algorithm utilizes the high occurrence of zero coefficient obtained by the previous thresholding process by re-allocating the zero and non-zero coefficients in different groups for quantization. Then, quantization error minimization mechanism is employed by calculating the median quantization error at each quantization interval class. The results are then compared to the existing algorithms and it is found that the proposed compression algorithm shows double increase in compression ratio performance, produces higher image quality with PSNR value above 40dB and ensures a better bit saving with smooth control at bit rate higher than 4 bpp. Thus, the proposed algorithm provides an alternative technique to compress the digital image