Study mass transfer of Cd, Hg, As, DDT and chlordane through adsorption onto granular activated carbon

The kinetic theory of liquid indicates that diffusion coefficient for the dilute liquid at ordinary pressure is essentially independent of mixture composition. Mass transfer is important in separation and adsorption process. However, diffusion may also be caused by other features. Because of the complex nature of mass diffusion, the diffusion coefficients are usually determined experimentally. The mass transfer resistance controls the kinetic adsorption rate, but there is only limited understanding of the adsorption of a solute onto porous material from surface water. Thus, this study was conducted to further enhance the understanding of the mass transfer and adsorption processes of micropollutants. The objectives of this study are to analyze the difference, examine the adsoprtion diffusion of mass transfer and evaluate the variation of total, internal and external mass transfer. This study also used the transformed equation to analyze the rate of adsorption during adsorption process onto different GACs. Five (5) micropollutants namely Hg, Cd, As, DDT and chlordane have been chosen to be adsorbed onto three (3) granular activated carbon which are SIG (shell industrial grade), SAG (shell analytical grade) and BAG (bitumen analytical grade). The micropollutants (Hg, Cd, As, DDT and chlordane) were prepared using standard stock solution in deionized water. Adsorption of pollutants onto SIG, SAG, and BAG were started at different percentages of outflow. Although the samples were taken at the same time, the outcome showed that a significant competition between adsorbates and adsorbents. From the analysis, SIG and SAG displayed excellent performance in adsorbing inorganic micropollutants while BAG for organic micropollutants. Before adsorption takes place, the morphology of the SAG indicated pore abundance compared to SIG and BAG. BAG pores are more structured than SIG and SAG. After adsorption occurs, more of the organic micropollutants are being adsorbed onto BAG and SAG. Meanwhile, SIG proved to be the best adsorbent for inorganic micropollutants. It takes 72 hours for Hg vi and As to saturate SIG whilst Cd take a longer time of 80 hours. SAG was also a good adsorbent for organic elements, with DDT taking 52 hours and chlordane taking 48 hours to be adsorbed. The [KLa]f value for the adsorption of Hg onto SIG was significant and the [KLa]d value for the adsorption of Hg onto SIG was higher onto SAG and BAG. The value of [KLa]f for SIG at 6% outflow was 0.6862 h-1, with values of [KLa]d at -0.4142 h-1 and [KLa]g at 0.2721 h-1, while for the adsorption of Cd it was shown that the [KLa]f values for the adsorption of Cd onto BAG was the most significant and the [KLa]d values for the adsorption of Cd onto SIG was higher than SAG and BAG at 2% outflow, with values of 0.7044 h-1, [KLa]d at -0.3687 h-1, and [KLa]g at 0.3356 h-1. In contrast, for As the [KLa]f for the adsorption of As onto BAG at 4% outflow was 0.6722 h-1 and [KLa]g was 0.3103 h-1. For DDT, the [KLa]f value of DDT for BAG at 0.5% outflow was 1.6662 h-1, [KLa]d was -1.2702 h-1 and [KLa]g was 0.3959 h-1. In the case of DDT, the value of [KLa]f for the adsorption of chlordane onto BAG at 2% outflow was 0.7330 h-1 and [KLa]d was started to activate the adsorption -0.5567 h-1. [KLa]g at 2% outflow was 0.1763 h-1. From these values we can conclude that for the adsorption of inorganic substances, SIG proved to be the best, while for organic substances BAG is the best adsorbent

Agonistic behavior of captive saltwater crocodile, crocodylus porosus in Kota Tinggi, Johor

Agonistic behavior in Crocodylus porosus is well known in the wild, but the available data regarding this behavior among the captive individuals especially in a farm setting is rather limited. Studying the aggressive behavior of C. porosus in captivity is important because the data obtained may contribute for conservation and the safety for handlers and visitors. Thus, this study focuses on C. porosus in captivity to describe systematically the agonistic behaviour of C. porosus in relation to feeding time, daytime or night and density per pool. This study was carried out for 35 days in two different ponds. The data was analysed using Pearson’s chi-square analysis to see the relationship between categorical factors. The study shows that C. porosus was more aggressive during daylight, feeding time and non-feeding time in breeding enclosure (Pond C, stock density =0.0369 crocodiles/m2) as compared to non-breeding pond (Pond B, stock density =0.3317 crocodiles/m2) where it is only aggressive during the nighttime. Pond C shows the higher domination in the value of aggression in feeding and non-feeding time where it is related to its function as breeding ground. Chi-square analysis shows that there is no significant difference between ponds (p=0.47, χ2= 2.541, df= 3), thus, there is no relationship between categorical factors. The aggressive behaviour of C. porosus is important for the farm management to evaluate the risk in future for the translocation process and conservation of C. porosus generally

Survey and Benchmark of Block Ciphers for Wireless Sensor Networks

Cryptographic algorithms play an important role in the security architecture of wireless sensor networks (WSNs). Choosing the most storage- and energy-efficient block cipher is essential, due to the facts that these networks are meant to operate without human intervention for a long period of time with little energy supply, and that available storage is scarce on these sensor nodes. However, to our knowledge, no systematic work has been done in this area so far.We construct an evaluation framework in which we first identify the candidates of block ciphers suitable for WSNs, based on existing literature and authoritative recommendations. For evaluating and assessing these candidates, we not only consider the security properties but also the storage- and energy-efficiency of the candidates. Finally, based on the evaluation results, we select the most suitable ciphers for WSNs, namely Skipjack, MISTY1, and Rijndael, depending on the combination of available memory and required security (energy efficiency being implicit). In terms of operation mode, we recommend Output Feedback Mode for pairwise links but Cipher Block Chaining for group communications

A dynamical systems approach to the discrimination of the modes of operation of cryptographic systems

Evidence of signatures associated with cryptographic modes of operation is established. Motivated by some analogies between cryptographic and dynamical systems, in particular with chaos theory, we propose an algorithm based on Lyapunov exponents of discrete dynamical systems to estimate the divergence among ciphertexts as the encryption algorithm is applied iteratively. The results allow to distinguish among six modes of operation, namely ECB, CBC, OFB, CFB, CTR and PCBC using DES, IDEA, TEA and XTEA block ciphers of 64 bits, as well as AES, RC6, Twofish, Seed, Serpent and Camellia block ciphers of 128 bits. Furthermore, the proposed methodology enables a classification of modes of operation of cryptographic systems according to their strength.Comment: 14 pages, 10 figure

Supervisory control for conventional unitary air conditioning system

The Supervisory control for conventional unitary air conditioning system is conceptually designed based on Programmable Logic Control (PLC) system. The advantage of PLC system is that it allows online monitoring continually and updates or modification can be performed interactively. This supervisory mode is applied to the conventional unitary air conditioner to avoid the frequent interruption or adjustment of the fan speed or temperature set point by users normal practice which has contributed to the surge of energy consumption due to the frequent on/off of the compressor. Three experiments have been performed at different control methods to simulate user’s daily practice. The first control method is the Variable Set point with high speed fan, the second control method is the Fixed Set point with high speed fan and the third control method is a Supervisory Control; a fixed set point with variable fan speed. The experiments have been conducted for eight (8) hours and the statistic data of accumulated energy consumption based on one unitary air conditioner with capacity of 1 Horse Power are acquired and sampled at the time interval of 30 minutes for the analysis. From these experiments, the supervisory control has consumed 4.2 kWh per day which is 82.35% compared to normal consumption of 5.1 kWh. This result translated into 0.9 kWh or 17.65% of total energy saving per day. The consistency of the air compressor operation in this control method has become a major factor in achieving indoor temperature steadiness whilst improving the energy savings

Analisis Perbandingan Kinerja Algoritma Kriptografi Serpent dan Twofish pada Dataset "World Bank Projects and Operations"

Serpent dan Twofish merupakan algoritma kriptografi yang menduduki peringkat kedua dan ketiga dalam kompetisi Advanced Encryption Standard (AES). Penelitian ini bertujuan untuk mengetahui algoritma mana yang lebih unggul dalam proses enkripsi dan dekripsi suatu file, serta keamanan kedua algoritma dalam menahan serangan brute force. Sebagai simulasi, enkripsi dan dekripsi kedua algoritma akan diterapkan pada dataset World Bank Projects and Operations. Sebelum enkripsi, file dataset yang digunakan akan dibagi menjadi beberapa file-file sampel berdasarkan jumlah kolom data. Kemudian file-file sampel yang sudah dienkripsi akan didekripsi dengan serangan brute force. Pada pengujian pertama, untuk kunci 128 bit, kecepatan rata-rata untuk enkripsi dan dekripsi Twofish 35% dan 43% lebih tinggi daripada Serpent. Pada kunci 192 bit, kecepatan rata-rata untuk enkripsi dan dekripsi Twofish 40% dan 48% lebih tinggi daripada Serpent. Pada kunci 256 bit, kecepatan rata-rata untuk enkripsi dan dekripsi Twofish 42% dan 48% lebih tinggi daripada Serpent. Pengujian kedua menunjukkan bahwa kecepatan serangan brute force tidak terpengaruh oleh ukuran kunci. Kecepatan rata- rata serangan brute force pada Twofish 56% lebih tinggi daripada Serpent. Meski dengan perbedaan kecepatan serangan yang tinggi, mendekripsi file yang dienkripsi oleh Twofish tetap memerlukan waktu berabad-abad. Hal ini disebabkan oleh kombinasi kunci yang banyak sekali bahkan pada kunci 128-bit. Secara keseluruhan, Twofish lebih unggul daripada Serpent tanpa mengorbankan sisi keamanan Twofish terhadap serangan brute force

ANALISIS PERBANDINGAN HASIL ENKRIPSI DAN DESKRIPSI ALGORITMA KRIPTOGRAFI RIJNDAEL DAN TWOFISH UNTUK PENYANDIAN DATA

Pada zaman modern ini, kemajuan teknologi sudah sangat pesat sehingga dataatau informasi perlu diamankan secara ketat untuk menjaga kerahasiaannya. Kriptografisendiri merupakan salah satu ilmu untuk mengamankan data atau informasi dari pihak lainyang mencoba meretas informasi tersebut. Dengan kriptografi data atau informasi bisasampai kepada pihak yang dituju tanpa diretas oleh pihak lain yang tidak mengetahuikuncinya. Maka di penelitian ini akan dilakukan perbandingan algoritma kriptografi Rijndaeldan algoritma Twofish, untuk mengetahui kecepatan waktu proses enkripsi dan dekripsimenggunakan panjang kunci yang berbeda, 128 bit dan 256 bit juga untuk mengetahuiapakah ada perubahan ukuran file sebelum dan sesudah di enkripsi menggunakan algoritmakriptografi Rijndael dan algoritma Twofish. Dipilihnya algoritma kriptografi Rijndael danalgoritma Twofish karena ingin membandingkan kecepatan waktu enkripsi dan dekripsi jugaukuran file setelah di enkripsi menggunakan dua algoritma yang dinyatakan lemah padapenelitian sebelumnya. Penelitian ini menggunakan metodologi kuantitatif dikarenakan hasilyang didapat merupakan angka atau numerik. Penelitian ini pun menggunakan metodependekatan kausal komparatif karena membandingkan dua objek untuk mengetahui manayang lebih baik. Diuji menggunakan uji t 2 populasi. Hasil yang didapat pada penelitian iniyaitu untuk kecepatan waktu enkripsi menggunakan kunci 128 bit dan 256 bit, algoritmaRijndael lebih cepat dari algoritma Twofish. Untuk kecepatan waktu dekripsi menggunakankunci 128 bit dan 256 bit, algoritma Rijndael lebih cepat dari algoritma Twofish. Dan terakhiruntuk ukuran file setelah di enkripsi menggunakan kunci 128 bit dan 256 bit, tidak adaperubahan yang signifikan antara algoritma Rijndael dan algoritma Twofish