Efficient algorithm for current spectral density calculation in single-electron tunneling and hopping

This write-up describes an efficient numerical method for the Monte Carlo calculation of the spectral density of current in the multi-junction single-electron devices and hopping structures. In future we plan to expand this write-up into a full-size paper.Comment: 4 page

Improved detection of Probe Request Attacks : Using Neural Networks and Genetic Algorithm

The Media Access Control (MAC) layer of the wireless protocol, Institute of Electrical and Electronics Engineers (IEEE) 802.11, is based on the exchange of request and response messages. Probe Request Flooding Attacks (PRFA) are devised based on this design flaw to reduce network performance or prevent legitimate users from accessing network resources. The vulnerability is amplified due to clear beacon, probe request and probe response frames. The research is to detect PRFA of Wireless Local Area Networks (WLAN) using a Supervised Feedforward Neural Network (NN). The NN converged outstandingly with train, valid, test sample percentages 70, 15, 15 and hidden neurons 20. The effectiveness of an Intruder Detection System depends on its prediction accuracy. This paper presents optimisation of the NN using Genetic Algorithms (GA). GAs sought to maximise the performance of the model based on Linear Regression (R) and generated R > 0.95. Novelty of this research lies in the fact that the NN accepts user and attacker training data captured separately. Hence, security administrators do not have to perform the painstaking task of manually identifying individual frames for labelling prior training. The GA provides a reliable NN model and recognises the behaviour of the NN for diverse configurations

Fouling effect on controller tuning in membrane bioreactor filtration process

This paper presents an initial investigation on controller tuning with the effect on membrane fouling in submerged membrane bioreactor (SMBR). This work employed proportional integral derivative (PID) controller to control SMBR filtration process. The PID controller is tuned using three different methods which are Ziegler Nichols (ZN), Cohen Coon (CC) and integral time-weight absolute error (ITAE) tuning. The PID controller is used to control the SMBR filtration permeate flux. Transmembrane pressure (TMP) was observed during the filtration process that will determine fouling effect on controller tuning. The simulation work is done using artificial neural network (ANN) model that was developed in our previous work. Different set points were tested to see the robustness of the controller tuning. The overall result shows the ITAE tuning method performs better compare with other tuning methods in term of its overshoot, settling time and integral absolute error (IAE) with 0.66, 9.1 second and 82.68 respectively. This tuning method provides precise control performance in the same time it will prevent from decrement of flux in the filtration cycle

Perancangan Alat Bantu Mesin Bubut untuk Menaikkan Gaya Cekam (Studi Kasus untuk Produk Poolschif, Part dari Mikroskop Elektron)

Produk poolschijf merupakan bagian (part) dari mikroskop elektron berbentuk pipih karena itu sulit dicekamketikadimesin oleh mesin bubut CNC (Computer Numerical Control).Pada penelitian ini dilakukan perancangan alat bantu (fixture) untuk menaikkan gaya cekam ini agar dapat dipenuhi parameter permesinan optimum yang diinginkan. Parameter permesinan optimum yang ingin dicapai adalah kecepatan potong (cutting speed) 200 m/min, kecepatan makan (feed) 0,3 mm/put, kedalaman potong 1,5 mm pada kecepatan spindle 1500 rpmmenggunakan pahat insert Taegutec, grade TT5100(P20). Sebelumnya tanpa menggunakan alat bantu kondisi permesinan adalah kecepatan potong (cutting speed) 160 m/min, kecepatan makan (feed) 0,15 mm/put, kedalaman potong 1,0 mm. Dari hasil perancangan alat ini diperoleh kenaikkan gaya cekam 40,91% menjadi 2,2 Mpa sekaligus menurunkan gaya centrifugal serta menambah kekakuan benda kerja sehingga kondisi pemotongan optimum yang diinginkan dapat tercapai. Dipihak lain terjadi pengurangan waktu permesinan dan pengurangan bahan baku produk. Demikian penggunaan alat bantu ini dapat menurunkan ongkos produksi serta menghemat bahan baku

Aloe Vera Mucilage as Drag Reducing Agent in Oil-Water Flow

Drag reduction is the deliberate reduction of the frictional pressure drop in flow systems by the addition of heavy molecular weight polymeric materials as well as other means such as pipeline modifications. Environmentally friendly and cheaper heavy molecular weight polymeric drag reducing agents (DRAs) has become a necessity in the transportation of fluids particularly in the oil and gas industry. However, very few reports exist on the potentials of natural polymers such as extracts from the Aloe Vera plant. In this study, the effects of Reynolds number and polymer concentration on the drag reduction effectiveness of Aloe barbadensis miller were tested. An experimental flow facility using unplasticized  Polyvinylchloride (uPVC) pipe of 12 mm ID was constructed with diesel (density = 832 kg/m3, dynamic viscosity = 1.664 mPa.s at 25°C) and water (density = 1000 kg/m3, dynamic viscosity = 0.891 mPa.s at 25°C) as test fluids. Drag reduction as a function of Aloe polymer concentration in the range 50 ppm to 500 ppm and Reynolds number 20000<Re<90000 were investigated by comparing the U-tube manometer pressure drop readings with and without aloe polymer. The pressure drop difference expressed as a percentage of the pressure drop without aloe polymer is termed drag reduction and was used to demonstrate the effectiveness of the Aloe Vera extracts or polymer as a DRA. In single phase horizontal (water) flow, a maximum drag reduction of 64% (U = 4.67 m/s) was measured, while in multiphase horizontal flow, a maximum drag reduction of 53.80% (α = 25%, Um = 4.67 m/s) was measured. Furthermore, measurements showed that pipe inclination had minimal effect on the drag reduction achieved. It was deduced that Aloe Vera mucilage can be used as a drag reducing agent in oil-water flows for Reynolds number below 63,00

Analisis Faktor yang Memengaruhi Pembentukan Minat Berlangganan di Industri Video-on-demand di Indonesia

Penelitian ini mengukur minat pengguna video-on-demand di Indonesia dengan menggunakan model penelitian UTAUT2 yang telah dimodifikasi, dimana peneliti menganalisis variabel Performance Expectancy, Effort Expectancy, Social Influence, Facilitating Condition, Hedonic Motivation, Price Value, Habit, dan Content terhadap Behavioral Intention. Data didapat menggunakan survei online dan berhasil mengumpulkan 403 responden yang valid, dengan usia 15-60 tahun, dan telah menggunakan layanan video-on-demand, serta telah melewati masa percobaan (free trial). Seluruh data yang dikumpulkan telah memenuhi kriteria validitas dan realibilitas. Untuk menguji validitas dan realibilitas, peneliti menggunakan software SPSS versi 21. Selain itu, untuk menguji hipotesis, peneliti menggunakan Structural Equation Modeling (SEM) dengan menggunakan software SmartPLS versi 3.0. Hasil pengujian membuktikan bahwa terdapat 4 faktor yang memengaruhi Behavioral Intention, yaitu Habit, Content, Performance Expectancy. Dan Effort Expectancy. Dalam variabel moderator, maka variabel Age (Usia) memengaruhi Habit terhadap Behavioral Intention, sedangkan variabel moderator Gender (Jenis Kelamin) dan Income (Pendapatan) tidak berpengaruh. Penelitian ini juga mendapatkan hasil R^2 sebesar 0,655 dan masuk pada kategori moderat

SCREENHOUSE EVALUATION OF GROUNDNUT GENOTYPES FORNITROGEN FIXATION AND MAIZE VARIETIES FOR NITROGENUPTAKE EFFICIENCY

Phosphorus is important in the symbiotic association with the bacteria rhizobium, there by fixing atmospheric nitrogen. Due to low availability of the fertility status of most savannah soils, the objectives of this research were therefore; to estimate biological nitrogen fixation by the groundnut genotypes under low and high phosphorus conditions and to determine the nitrogen uptake efficiency of some selected maize varieties. To achieve these objectives, a potted experiment was conducted in the screenhouse of the Department of Soil Science, Ahmadu Bello University Samaru, Zaria. The treatments consisted of a combination of five genotypes of groundnut namely; (Samnut 10, Samnut 11, Samnut 21, Samnut 22 and Samnut 23) and three varieties of maize (TZE, TZEE, and Obatampa). The groundnut genotypes had 60kg P2O5 ha-1 (13.2 mgP/kg soil) and 0kg P2O5 ha-1 (0 mgP/kg soil), the maize varieties had 75 kg P2O5 ha-1 (16.5 mgP/ kg soil) and 0 kg P2O5 ha-1 (0 mgP/ kg soil) levels. The treatments were repeated three times and laid down in a Completely Randomised Design. There was no significant difference in the amount of atmospheric nitrogen fixed by the groundnut genotypes. However, Phosphorus application significantly increased nitrogen fixation compared to the control, therefore 60kg P2O5 ha-1 is concluded for higher nitrogen fixation in the soil.The effect of maize varieties in relation to nitrogen uptake efficiency was significant statistically, this result shows that the varieties that grow and develop extra early takes up more nitrogen faster than the late varieties and early varieties

Experimental assessment of the performance of reinforced concrete beams strengthened with carbon fiber reinforced polymer laminates

In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are made that externally application of CFRP laminates can be used for a significant enhancement of the strength deficient RC beams in increasing the ultimate load carrying capacity. Keywords: CPRP laminate, Reinforced concrete, ductility, index, epoxy resin, flexural strengthenin