Research in nonlinear structural and solid mechanics

Recent and projected advances in applied mechanics, numerical analysis, computer hardware and engineering software, and their impact on modeling and solution techniques in nonlinear structural and solid mechanics are discussed. The fields covered are rapidly changing and are strongly impacted by current and projected advances in computer hardware. To foster effective development of the technology perceptions on computing systems and nonlinear analysis software systems are presented

Analisa Pengaruh Disiplin Kerja dan Stress Kerja terhadap Prestasi Kerja Pegawai Bandar Udara H. Asan di Sampit

Pembahasan ini dilakukan mengacu pada tujuan penelitian yang didasarkan pada hasil-hasil statistik yang diperoleh. Untuk mencapai tujuan tersebut diperlukan Regresi Linier Berganda dengan program SPSS for windows 16.0 maka diperoleh persamaan regresi linier berganda:Y = a +Y = 9,057+ 0,256 (X1) + 0,299 (X2) Pada persamaan tersebut menunjukkan tingkat korelasi atau hubungan antara variabel independen yaitu disiplin kerja (X1) dan stress kerja (X2) terhadap dependen yaitu prestasi kerja pegawai (Y). Untuk mengetahui besar pengaruh tiap variabel independen terhadap dependen. Persamaan regresi tersebut dapat dijelaskan sebagai berikut:1). Berdasarkan hasil uji-t setiap variabel independen atau secara individu terbukti memiliki pengaruh terhadap variabel dependen. Hal ini terbukti dengan hasil perhitungan uji statistik yang menunjukkan thitung ˃ t table dan juga diikuti dengan nilai probabilitas ˂ 0,05 maka H0 ditolak (Ha diterima). Dimana disiplin kerja (X1) dengan thitung (2,031) ˃ t table (2,0117) dengan tingkat signifikan sebesar( 0,048 ˂ 0,05) dan stress kerja (X2) dengan thitung (2,611) ˃ ttabel (2,0117) dengan tingkat signifikan ( 0,012 ˂ 0,05). Sehingga dari hasil uji t menunjukkan bahwa variabel stress kerja (X2) memiliki pengaruh yang lebih besar terhadap prestasi kerja (Y) dari pada variabel disiplin kerja (X1). Dapat dilihat di uji t pada tabel 4.2). Dari perhitungan uji F , maka kita perlu tarik kesimpulan bahwa variabel independen (variabel disipilin kerja (X1) dan stress kerja (X2) ) secara bersama-sama memiliki pengaruh signifikan terhadap variabel dependen yaitu prestasi kerja (Y). Hal tersebut dapat dilihat dari hasil fhitung pada tabel 4.. Dimana fhitung˃ ftabel dengan tingkat signifikan sebesar 0,05 yaitu fhitung (10,592) ˃ ftabel (3,1950) dengan signifikasi 0,000 ˂ 0,05.3). Pada model summary tabel 4.., angka R sebesar 0,557 artinya disiplin kerja (X1) dan stress kerja (X2) memiliki hubungan yang cukup kuat terhadap prestasi kerja pegawai (Y) pada Bandar Udara H. Asan Sampit. Disebut cukup kuat karena berada diatas atau dengan angka yang lebih besar dari R square 0,311 (31,1 %).4). Dari perhitungan koefisien determinasi (r2) juga menunjukkan hasil bahwa variabel-variabel independen yang ada mempengaruhi peningkatan prestasi kerja (Y) sebesar 31,1%. Sedangkan sisanya 68,9% dijelaskan oleh variabel lain selain kedua variabel tersebut seperti motivasi, pendidikan, kepuasan kerja dan lingkungan kerja

UJI AKTIVITAS ANTIBAKTERI EKSTRAK ETANOL DAUN SIRIH MERAH (Piper crocatum) TERHADAP Pseudomonas aeruginosa DAN Shigella dysenteriae BESERTA BIOAUTOGRAFINYA

Dalam bidang kesehatan, infeksi merupakan penyebab utama penyakit dunia terutama di daerah tropis yang disebabkan oleh berbagai mikroorganisme. Pseudomonas aeruginosa dan Shigella dysenteriae merupakan contoh bakteri yang dapat menyebabkan infeksi dan merupakan golongan bakteri Gram negatif. Tanaman yang dapat dimanfaatkan untuk obat menangani infeksi diantaranya adalah Sirih merah (Piper crocatum). Penelitian ini dilakukan untuk mengetahui aktivitas antibakteri ekstrak etanol daun sirih merah (Piper crocatum) terhadap P. aeruginosa dan S. dysenteriae. Pada penelitian ini proses ekstraksi dilakukan dengan metode maserasi dengan penyari etanol 96%. Uji aktivitas antibakteri dilakukan dengan metode dilusi padat dengan seri konsentrasi ekstrak untuk uji P. aeruginosa adalah 3%, 4%, 6%, dan 7% sedangkan konsentrasi ekstrak untuk S dysenteriae adalah 2%, 4%, 5%, dan 6%. Ekstrak kemudian dianalisis kandungan kimianya menggunakan metode KLT dengan fase gerak berupa metanol : kloroform (1:39). bioautografi untuk mengetahui senyawa yang berperan sebagai antibakteri. Hasil penelitian menunjukkan bahwa ekstrak etanol daun sirih merah memiliki aktivitas terhadap P.aeruginosa dan S. dysenteria dengan nilai Kadar Bunuh Minimum berturut-turut sebesar 6% dan 5%. Hasil uji KLT menunjukkan bahwa ekstrak etanol daun sirih merah mengandung golongan senyawa terpenoid, flavonoid, dan alkaloid. Uji bioautografi menunjukkan bahwa senyawa yang memiliki aktivitas antibakteri adalah flavonoid dan terpenoid

Analysis and Assessment of Essential Toxic Heavy Metals, PH and EC in Ishaqi River and Adjacent Soil

This research was conducted to determine content levels of heavy metal pollution.  Samples taken from Ishaqi River bank and adjacent agricultural soils area, in ten sites, distributed along 48 km of the Ishaqi River, north Baghdad. The evaluated metals were Zinc, Copper, Manganese, Iron, Cobalt, Nickel, Chromium, Cadmium, Vanadium and Lead. PH and Electric Conductivity (EC) were measured to evaluate the acidity and (EC). Results showed that most site were contaminated with metals evaluated. Among these metals, Zn, Mn, Fe and Ni were consistently higher in all the samples (both river bank and adjacent soil) followed by PB, CU, V, Cd, Co and Cr. The level concentrations of river bank were almost higher than that of adjacent soil. As will be reported later, the concentrations of Nickel, Zinc, Manganese and Iron in river bank and agricultural adjacent soil were over the permissible levels. The average mean levels were (Ni 66.36 mg/kg, Zn 42.59 mg/kg, Mn 26.78 mg/kg, Fe 25.15 mg/kg) in river bank and (Ni 46.31 mg/kg, Zn 33.06 mg/kg, Mn 20.78 mg/kg Fe 16.28 mg/kg) in agricultural adjacent soil. Overall, Nickel had the highest concentrations in the ecosystem. Keywords: heavy metals, environmental pollution, river bank, adjacent soil, AAS

Intrinsic conducting polymer current limiting device

This thesis investigates the development of novel intrinsic conducting polymer current limiting devices (CLDs), which are small self-resettable components used to protect circuitry in portable electronic appliances during situations of overcurrent. There are many existing solutions that enable the interruption and limitation of current surges in devices. A simple and common device is the use of a hybrid system of small metallic/semiconducting particles embedded in a thermally responsive polymeric material. During an overcurrent situation the positive temperature coefficient resistance (PTCR) of the polymeric material expands due to joule heating, which causes the percolating current pathways in the device to break which in turn causes the device to become temporarily non conducting. Although commonly used in the electronics industry today there are some limitations in the conductive fillers such as fretting and degradation that cause unwanted shifts in the percolation threshold, which can result in faulty operation. There is also increasing demand for faster operating devices as well as cheaper and more convenient methods of fabrication. One possibility that has emerged is the use of intrinsic conducting polymers as current limiting materials. There are several benefits of this for commercialization, such as cheap starting materials, simple chemical or electrochemical solution-based methods for device fabrication and potentially very fast device operation if the mechanism is electronic rather than mechanical in nature. Although preliminary measurements in these materials have shown evidence of switching to a non-conducting state at high currents, which is resettable upon cooling, the mechanism that causes the switching has not been established and no studies on this effect have been reported in the literature.This motivates further work into developing current limiting devices based on these materials. The intention of this research is (1) to develop current limiting devices based on the intrinsic conducting polymer polyaniline (PANI), (2) to improve the electronic properties of the device, ideally we desire to have low resistance at low current level (normal operating conditions) and saturated or limited conductivity at high current level (overcurrent/short-circuit conditions), (3) elucidate the switching mechanism of the devices and (4) investigate the devices stability and resetability characteristics in different environmental conditions.The results of this thesis show that the presence of moisture in the conducting polymer plays an important role in the current limiting performance. Our results indicate that the electronic switching of the devices is a result of a partial de-doping/re-doping effect caused by water diffusing into and out of the polymer film during joule heating/ cooling of the devices. We speculate that the polymer/metal interface region plays an important role in this and as such significant improvement in the electrical properties were made using self-assembled monolayer (SAM) modified electrodes.Studies were also performed to understand the temperature dependent electrical resistivity of the polymer material, shown to be variable range hopping in three dimensions, and as well, investigations were made to understand device performance in different environmental conditions (varying from vacuum to 100% relative humidity). Stability and degradation testing was performed in order to find the best operational and stable conditions for the current limiting devices. Results showed that devices were very stable in low to medium voltage values. In an effort to understand the effect of dopant type on the moisture content in the polymer film, thermal analyses (thermogravimetric and differential scanning calorimetry) of samples with different dopants were investigated. Polyaniline doped with methanesulfonic acid was found to be among the samples with the highest moisture content

Tracing and Analysis of Manganese, Nickel, Cadmium ,Copper, zinc , Lead And Aluminum Concentration and PH Values In Iraqi Chewing Gums

Evaluation of trace elements in Iraqi chewing gums are unavailable, particularly pollution of toxic elements, materials which change the values of PH in the Oral. Atomic Absorption Spectroscopy (AAS) were successfully employed to determine the concentration of 7 trace elements (essentially toxic and nonessential) and the PH, in thirteen different brands of chewing gum generally consumed in Iraq. Combined wet and dry digestion procedures were applied. Two types of heated graphite tubes were used, coated and uncoated tubes treated with tungsten solution. Result showed that Cu, Al and Zn were at very high levels in almost all brands whereas Mn was found to be high in brands A and O only. Keywords: Trace metals – heavy elements, Chewing gums - AAS-  Baghdad – Iraq