643 research outputs found
Synthesis of Fatty and N,N'-carbonyl Difatty Amides from Palm Oil and Their Applications as a Clay Modifier for Polylactic Acid/Epoxidized Palm Oil/Clay Nanocomposites Preparation
N,N-carbonyl difatty amides (CDFAs) were synthesized from palm oil and urea using sodium ethoxide as a catalyst. Ethyl fatty esters (EFEs) and glycerol were produced as by-products. The synthesis was carried out by refluxing the reactants in ethanol. In this reaction, palm oil gave 79% CDFAs after 8 h and at molar ratio of urea to palm oil of 6.2: 1. Meanwhile, fatty amides (FAs) were synthesized from palm olein and urea by a one-step lipase catalyzed reaction. The use of immobilized lipase as the catalyst for the preparation reaction provides an easy isolation of the enzyme from the products and other components in the reaction mixture. The highest conversion percentage of 96% was obtained when the process was carried for 36 h using urea to palm olein ratio of 5.2: 1.0 at 40 ºC. The method employed offers several advantages such as the use of renewable and abundant of the raw material, simple reaction procedure, environmentally friendly process and high yield of the product.
Both CDFAs and the FAs were characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) technique and elemental analysis. The CDFAs, FAs and fatty hydroxamic acids (which were also synthesized from palm oil) were used as organic compounds to modify natural clay, Na-MMT, (sodium montmorillonite) by an ion exchange process. The clay modification was carried out by stirring the clay particles in an aqueous solution of FAs, CDFAs and fatty hydroxamic acids (FHAs). The interaction of the modifier in the clay layer was characterized by X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Elemental analysis was used to estimate the presence of these fatty nitrogen compounds (FNCs) in the clay. The modified clay was then used in the preparation of the polylactic acid (PLA)/epoxidized palm oil (EPO) blend nanocomposites.
The EPO was used as a plasticizer for PLA using chloroform as a solvent for solution casting process of blending PLA/EPO. The FTIR spectra indicate that there are some molecular interactions by intermolecular hydrogen bond between PLA and EPO. All PLA/EPO blends show high thermal stability and significant improvement of mechanical properties compare to those of pure the PLA. The highest elongation at break (about 210%) was obtained when the ratio of PLA/EPO blend was 80/20. Morphological results of PLA/EPO blends show that EPO was miscible with PLA. Reduced viscosities of the blends decrease with increasing amount of EPO indicating that EPO was a good plasticizer for PLA.
The nanocomposites were synthesized by incorporating CDFA-MMT, FA-MMT or FHA-MMT into PLA/EPO blends. Preparation of nanocomposites were carried out by solution casting of the modified clay and PLA/EPO blend of the weight ratio of 80/20 which has the highest elongation at break. The highest tensile strength, modulus, and elongation at break of the FA-MMT, FHAMMT, and CDFA-MMT nanocomposites were obtained when 2% of the CDFA-MMT and 3% of both FA-MMT and FHA-MMT loadings were used. These nanocomposites were characterized using XRD, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and tensile properties measurements. The XRD and TEM results confirm that the products are nanocomposites. PLA/EPO modified clay nanocomposites has higher thermal stability and significant improvement of mechanical properties in comparison with those of the PLA/EPO blend
Implementation of Simple Measures for Savings Water and Energy Consumption in Kuwait Government Buildings
This paper gives in details the efforts made by the Public Services Department (PSD) to
reduce water and energy consumptions in the Ministry of Social Affairs and Labour's
(MOSAL) buildings in Kuwait. PSD manages around 125 buildings distributed over 6
governorates. PSD's efforts included the installation of programmable thermostats for A/C
units, urging MOSAL's staff to switch off lighting after working hours, replacement of old
A/C and lighting systems by newer systems and installation of shutters and solar films for
windows, insulation materials for walls and roofs and low-flow water tools for faucets. These
efforts reduced the overall water and energy consumptions by 15 and 25%, respectively, in all
MOSAL's buildings. Additionally, MOSAL is planning to collaborate with Kuwait Institute
for Scientific Research (KISR) to further reduce water and energy consumptions in
MOSAL's buildings by optimizing operation strategies and utilizing new water and energy
technologies
Affordable Frequency Selective Hearing Amplifier
One of the most prevalent diseases affecting human communication is hearing loss. About one in every six people has a hearing deficit globally. Many people suffer from hearing loss but cannot afford a hearing aid because of the high cost set by manufacturers. In this study, we aim to design a frequency-selective hearing amplifier that could be used as an alternative to hearing aids by having an external controller and separate earpieces. The controller allows the user to select the correct frequency bands to be amplified according to the listeners’ degree of hearing loss. As a starting point, we have divided the frequency range of hearing into three bands: 125 Hz to 1 kHz, 1 Hz to 4 kHz, and 4 Hz to 8 kHz. The microphone picks up the signal, and the Analog-to-Digital Converter (ADC) converts the signal to digital form which then goes through a microcontroller where filtering and amplification take place. The amplified frequency band of the signal is then added to the rest of the signal and rescaled before a Digital-to-Analog Converter (DAC) converts the signal to an analog form. Analog signals would go through a second amplifier to adjust the overall speech level that can be heard via the earpiece. The circuit components in the amplifier could be adjusted to produce the desired amount of amplification. The proposed design is tested thoroughly to ensure that a wide range of amplification is achieved for a wide range of listeners with various degrees of hearing loss
Smart Operations of Air-Conditioning and Lighting Systems in a Government Buildings for Peak Power Reduction
This paper presents the achievements of implementing smart operations strategies for air-conditioning (A/C) and lighting systems in Justice Palace Complex (JPC), Kuwait during the summer 2007. The peak load of this building was 3700 kW. The achievements are summarized as direct savings between 13:00 and 22:00 h by closing supply and return air fans of 52 air-handling units with a connected load 400 kW, and an additional saving of 550 kW during the same period by optimizing the cooling production and distribution. Also an all time saving of 22 kW by de-lamping, and additional saving of 27 kW through TDC of lighting were achieved. In conclusion project achieved an overall reduction in power demand of around 20% between 13:00 to 17:00 h and reduction ranging from 7% to 15% between 17:00 to 20:00 h
Implementation of Simple Measures for Savings Water and Energy Consumption in Kuwait Government Buildings
This paper gives in details the efforts made by the Public Services Department (PSD) to
reduce water and energy consumptions in the Ministry of Social Affairs and Labour's
(MOSAL) buildings in Kuwait. PSD manages around 125 buildings distributed over 6
governorates. PSD's efforts included the installation of programmable thermostats for A/C
units, urging MOSAL's staff to switch off lighting after working hours, replacement of old
A/C and lighting systems by newer systems and installation of shutters and solar films for
windows, insulation materials for walls and roofs and low-flow water tools for faucets. These
efforts reduced the overall water and energy consumptions by 15 and 25%, respectively, in all
MOSAL's buildings. Additionally, MOSAL is planning to collaborate with Kuwait Institute
for Scientific Research (KISR) to further reduce water and energy consumptions in
MOSAL's buildings by optimizing operation strategies and utilizing new water and energy
technologies
Prevalence of somatisation and psychologisation among patients visiting primary health care centres in the State of Qatar
Background: Medically unexplained somatic complaints are among the most common clinical presentations in primary care in developing countries and they are considerable burden for patients and health care system. Objectives: The aim of this study was to determine the prevalence of somatisation in comparison to psychologisation among a sample of Qatari patients who were visiting primary health care (PHC) centres and to investigate the clinical and socio-demographic characteristics of somatisers (STs) and psychologisers (PGs). Method: The survey was conducted among PHC Qatari patients during the period from January to July 2007. About 2,320 patients were approached, of whom 1,689 agreed to participate and responded to the questionnaire. Among the studied Qatari patients, 404 patients were identified for clinical interview. The first stage of the study was conducted with the help of general practitioners, using the 12-item General Health Questionnaire. The second stage was carried out by a consultant using the Clinical Interview Schedule. A specific operational criterion was used to identify STs and PGs. Results: The prevalence rate of STs among the total studied sample was 12.4%, while the PGs were 11.5%. Among the identified psychiatric cases, the proportion of STs (52%) was higher than PGs (48%). Most of the diagnostic categories were more prevalent among PGs. The dissatisfaction at work and stressful life events within 12 months before the onset of the presenting symptoms were the three postulated determinants which were significantly more among STs than PGs. Conclusion: The prevalence of somatised mental disorder was little higher than the psychologised mental disorder. The prevalence of somatisation and psychologisation is comparable with other reported studies from the Middle-East and Western countries. Dissatisfaction at work and stressful life events were significantly higher among STs than PGs.Keywords: somatisers; psychologisers; primary health care; determinants; Arab cultur
Utilizing Distributed Temperature Sensors in Predicting Flow Rates in Multilateral Wells
The new advancement in well monitoring tools have increased the amount of data that could be retrieved with great accuracy. Downhole pressure and temperature could be precisely determined now by using modern instruments. The new challenge that we are facing today is to maximize the benefits of the large amount of data that is being provided by these tools and thus justify the investment of more capital in such gadgets. One of these benefits is to utilize the continuous stream of temperature and pressure data to determine the flow rate in real time out of a multilateral well. Temperature and pressure changes are harder to predict in horizontal laterals compared with vertical wells because of the lack of variation in elevation and geothermal gradient. Thus the need of accurate and high precision gauges becomes critical. The trade-off of high resolution sensors is the related cost and resulting complication in modeling. Interpreting measured data at real-time to a downhole flow profile in multilateral and horizontal wells for production optimization is another challenge.
In this study, a theoretical model is developed to predict temperature and pressure in trilateral wells based on given flow conditions. The model is used as a forward engine in the study and inversion procedure is then added to interpret the data to flow profiles. The forward model starts from an assumed well flow pressure in a specified reservoir with a defined well structure. Pressure, temperature and flow rate in the well system are calculated in the motherbore and in the laterals. These predicted temperature and pressure profiles provide the connection between the flow conditions and the temperature and pressure behavior.
Then we use an inverse model to interpret the flow rate profiles from the temperature and pressure data measured by the downhole sensors. A gradient-based inversion algorithm is used in this work, which is fast and applicable for real-time monitoring of production performance. In the inverse model, the flow profile is calculated until the one that generates the matching temperature and pressure profiles in the well is identified. The production distribution from each lateral is determined based on this approach.
At the end of the study, the results showed that we were able to successfully predict flow rates in the field within 10% of the actual rate. We then used the model to optimize completion design in the field.
In conclusion, we were able to build a dependable model capable of predicting flow rates in trilateral wells using pressure and temperature data provided by downhole sensors
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