Hygrothermal performance of building envelopes in the tropics under operative conditions : condensation and mould growth risk appraisal

Poor indoor hygrothermal performance increases the risk of indoor moisture problems and deterioration due to mould growth, corrosion and damage to archival materials. Hence, proper control of indoor thermohygric intensity abates indoor moisture and its associated problems. This paper presents the results of envelopes hygrothermal performance assessments in a hot and humid climate building with varying operational profile between adjacent spaces. The case-studied building runs on 24hrs cooling mode in one part against natural and/or mechanical supply-exhaust fan means on the other. In-situ experiments were combined with hygrothermal analytical methods to assess the envelope thermal quality together with the operative conditions against condensation and mould growth risks. The results show that the building is overcooled leading to poor envelope hygrothermal performance with associated condensation and mould growth problems on non-airconditioned sides of the envelopes

Electrical discharge machining of polycrystalline diamond using copper electrode – finishing condition

Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1µs. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4µm was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1µs and 1µs respectively

Kritik al-Quran oleh Nasr Hamid Abu Zayd melalui terapan hermeneutics humanistic

Nasr Hamid Abu Zayd dikenali sebagai seorang tokoh yang lantang mengkritik al-Quran pada abad ini. Beliau mempunyai metode yang tersendiri ketika mentafsir al-Quran iaitu mengaplikasi hermeneutik dengan menerapkan elemen humanistic. Artikel ini bertujuan untuk menganalisis elemen humanistic yang dibawa oleh Abu Zayd dalam empat aspek iaitu definisi al-Quran, konsep bahawa wahyu, proses penurunan wahyu dan metode pentafsiran. Empat aspek tersebut dibandingkan secara berterusan dengan al-Quran dan al-Sunnah. Untuk mencapai validity data, artikel yang bersifat kualitatif ini menggunakan metode analisis kandungan yang terdiri daripada karyakarya Abu Zayd sebagai sumber pengumpulan data. Manakala analisis data menggunakan kaedah diskriptif dan perbandingan berterusan. Hasil kajian menunjukkan, elemen humanistic yang telah diterapkan kepada al-Quran telah mencetuskan implikasi terhadap al- Quran, konsep wahyu, tafsiran relatif dan liberalisasi hukum syariah

Electrical discharge machining of polycrystalline diamond using copper electrode – finishing condition

Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1µs. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4µm was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1µs and 1µs respectively

Influence of traffic vehicles against ground fundamental frequency prediction using ambient vibration technique

Ambient vibration (AV) technique is widely used nowadays for ground fundamental frequency prediction. This technique is easy, quick, non-destructive, less operator required and reliable result. The input motions of ambient vibration are originally collected from surrounding natural and artificial excitations. But, careful data acquisition controlled must be implemented to reduce the intrusion of short period noise that could imply the quality of frequency prediction of an investigated site. In this study, investigation on the primary noise intrusion under peak (morning, afternoon and evening) and off peak (early morning) traffic flows (only 8 meter from sensor to road shoulder) against the stability and quality of ground fundamental frequency prediction were carried out. None of specific standard is available for AV data acquisition and processing. Thus, some field and processing parameters recommended by previous studies and guideline were considered. Two units of 1 Hz tri-axial seismometer sensor were closely positioned in front of the main entrance Universiti Tun Hussein Onn Malaysia. 15 minutes of recording length were taken during peak and off peak periods of traffic flows. All passing vehicles were counted and grouped into four classes. Three components of ambient vibration time series recorded in the North-South: NS, East-West: EW and vertical: UD directions were automatically computed into Horizontal to Vertical Spectral Ratio (HVSR), by using open source software of GEOPSY for fundamental ground frequency, Fo determination. Single sharp peak pattern of HVSR curves have been obtained at peak frequencies between 1.33 to 1.38 Hz which classified under soft to dense soil classification. Even identical HVSR curves pattern with close frequencies prediction were obtained under both periods of AV measurement, however the total numbers of stable and quality windows selected for HVSR computation were significantly different but both have satisfied the requirement given by SESAME (2004) guideline. Besides, the second peak frequencies from the early morning HVSR curve was clearly indicated between 8.23 to 8.55 Hz at very low amplitude (Ao < 2), but it should be neglected according to the similar guideline criteria. In conclusion, the ground fundamental frequency using HVSR method was successfully determined by 1 Hz seismometer instrument with recommended to specific parameters consideration on field as well as data processing, without disruption from the nearest traffic excitations

Properties of fly ash concrete containing tropical soil bacteria

The autonomous crack healing process using microbiologically induced calcium carbonate precipitation (MICP) is a sustainable alternative to overcome propagation of micro-cracks and restore the durability of concrete. This paper presents the potential use of tropical soil bacteria as a self-healing agent for fly ash concrete. A solution of 107 cells/mL Lysinibacillus sphaericus (L. sphaericus), was selected to be the self-healing agent by replacing partially the amount of water. Concrete cube specimens with 30% fly ash, were cured under two conditions, which are water and air curing. The potential effects of the self-healing agent was evaluated in terms of the ultrasonic pulse velocity (UPV), initial surface absorption test (ISAT) and compressive strength. The initial results show an improvement of UPV and between 12% and 54% improvement on the compressive strength for the bacterial concrete compared to the control specimen. It was probably due to the presence of the microbial calcium carbonate that fills the concrete pores through the inclusion of bacteria in the concrete. However, based on the ISAT value, the direct addition of bacterial solution increased the concrete's permeability. Thus, further investigation is suggested to assess the self-healing effect towards permeability and compressive strength of bacterial concrete

Rapid Determination of Non-steroidal Anti-inflammatory Drugs in Aquatic Matrices by Two-phase Micro-electrodriven Membrane Extraction Combined with Liquid Chromatography

Two-phase micro-electrodriven membrane extraction (EME) procedure for the pre-concentration of selected non-steroidal anti-inflammatory drugs (NSAIDs) in aquatic matrices was investigated. Agarose film was used as interface between donor and acceptor phase in EME which allowed for selective extraction of the analytes prior to high performance liquid chromatography-ultraviolet detection. Charged analytes were transported from basic aqueous sample solution through agarose film into 1-octanol as an acceptor phase at 9 V potential. Response surface methodology in conjunction with the central composite design showed good correlations between extraction time and applied voltage (R 2 > 0.9358). Under optimized extraction conditions, the method showed good linearity in the concentration range of 0.5-500 μg L -1 with coefficients of determination, r 2 ≥ 0.9942 and good limits of detection (0.14-0.42 μg L -1) and limits of quantification (0.52-1.21 μg L -1). The results also showed high enrichment factors (62-86) and good relative recoveries (72-114%) with acceptable reproducibilities (RSDs ≤ 7.5% n = 3). The method was successfully applied to the determination of NSAIDs from tap water and river water samples. The proposed method proved to be rapid, simple and requires low voltage and minute amounts of organic solvent, thus environmentally friendly

Review of Polymer, Dye-Sensitized, and Hybrid Solar Cells

The combination of inorganic nanoparticles semiconductor, conjugated polymer, and dye-sensitized in a layer of solar cell is now recognized as potential application in developing flexible, large area, and low cost photovoltaic devices. Several conjugated low bandgap polymers, dyes, and underlayer materials based on the previous studies are quoted in this paper, which can provide guidelines in designing low cost photovoltaic solar cells. All of these materials are designed to help harvest more sunlight in a wider range of the solar spectrum besides enhancing the rate of charge transfer in a device structure. This review focuses on developing solid-state dye-synthesized, polymer, and hybrid solar cells

Stability studies of nano-cream containing piroxicam

The aim of this study is to study the stability of the nano-cream formula containing the newly synthesized palm oil esters when stored for reasonable storage duration. The prepared 0.5% piroxicam nano-cream formula contained phosphate buffer as external phase, palm oil esters as the oil phase and a combination of (80:20) of Tween 80 and Span 20 as emulsifier at a ratio of 37:25:38, respectively. Piroxicam is a hydro-lipophobic drug. Stability on storage is an important aspect which ensures the dosage form can exert the effects it is supposed to exert for the duration of storage. Droplets size, electrical conductivity, drug content, pH and rheological parameters are the parameters that have been assessed under different temperature to evaluate the stability of nano-cream preparation. Thus, experiments which measure the above parameters were conducted at storage temperatures of 4, 25 and 40οC.The data obtained from the stability study conducted on nano-cream formula showed that this formulation was stable for the whole 3 months period of the study when stored at tested several temperatures.Keywords: Palm oil esters; Nonionic surfactant; Piroxicam; Nano-crea