An empirical estimation of underground thermal performance for Malaysian climate

In this study, the soil temperature profile was computed based on the harmonic heat transfer equations at various depths. The meteorological data ranging from January, 1st 2016 to December, 31st 2016 measured by local weather stations were employed. The findings indicted that as the soil depth increases, the temperature changes are negligible and the soil temperature is nearly equal to the mean annual air temperature. Likewise, the results have been compared with those reported by other researchers. Overall, the predicted soil temperature can be readily adopted in various engineering applications in Malaysia

Effect of rake angle and feed rate on tool wear and surface topography for different chip size in machining carbon steels

This paper proposes tool wear and surface topography analyses in cutting carbon steels 1045 that producing different chip types. The problem of continuous chip due to the different rake angle and feed rate cause the reduction of the surface quality and tool life. The cutting rake angle is set based on the difference angle of shim support for the tool holder. Beside rake angle, different feed rate can improve the surface topography and the tool wear. Tests are carried out using carbon steel 1045 as workpiece material and chip breaker CNMG 120412 as tool insert under dry machining conditions. Results indicated that the lowest the tool wear, the better surface topography produced from the segmented chip at feed rate 0.4 mm/rev and a rake angle −9°. The effect of rake angle and feed rate overcome the problem of continuous chip that associated with low tool wear and surface topography

Heuristic design of U-shaped die cooling channel for producing ultra-high strength steel using hot press forming

This paper proposes an optimised cooling channel design for a U-shaped die in the hot sheet metal forming process using a heuristic method. Unlike in previous works, the parameters used in this study for optimising the cooling channel design not only consider the pitch between and diameter of cooling channels but also their distance from the tool surface and wall tool. The cooling channel design is optimised by coupling the heuristic method with finite element thermal and static analyses. The main factors to be considered in the optimisation include the highest heat transfer and the lowest stress that can be achieved by the optimum cooling channel die design. The optimum design was determined by conducting a simulation and was validated by conducting an experiment. The temperature distribution of the FEA model was at most 5% different from the experimental results. The optimum cooling channel design of hot press sheet metal forming can produce ultra-high strength steels which tensile strength and hardness are 51 and 83% greater than those of original boron steels. The heuristic method can also be applied to optimise the cooling channel die design for the production of ultra-high strength steels in the automotive manufacturing industry

Pemahaman, penghayatan dan pengamalan jati diri pelajar aliran pendidikan Universiti Awam

Kajian ini bertujuan mengenal pasti tahap pemahaman, penghayatan dan pengamalan jati diri dalam kalangan pelajar aliran pendidikan di lima buah Universiti Awam bertaraf Universiti Penyelidikan. Sebanyak tujuh konstruk jati diri diukur, iaitu agama, ilmu, nilai, bahasa, budaya, perpaduan dan semangat nasionalisme. Untuk itu, seramai 1000 orang pelajar, iaitu 200 orang bagi setiap sebuah Universiti Awam dijadikan responden kajian. Responden tersebut dipilih secara rawak mudah yang sedang melanjutkan pengajian dalam pelbagai program pendidikan di Fakulti Pendidikan di UKM, UPM, UM, USM dan UTM tersebut. Instrumen soal selidik digunakan untuk pengumpulan data. Data dianalisis secara deskriptif dan inferensi menggunakan Statistical Package for Social Sciences (SPSS) versi 23.0. Dapatan kajian menunjukkan bahawa pelajar aliran pendidikan Universiti Awam secara amnya masih mengekalkan jati diri dalam kesemua tujuh konstruk yang dikaji. Dari segi pemahaman, penghayatan dan pengamalan, hanya aspek bahasa sahaja yang berada pada tahap masih kekal jati diri, manakala enam jati diri lain yang dikaji (agama, ilmu, nilai, budaya, perpaduan dan semangat nasionalisme) berada pada tahap kekal (kukuh) jati diri mereka. Pelajar UM merupakan pelajar yang paling kurang pemahaman, penghayatan dan pengamalan jati diri bahasa Melayu mereka berbanding pelajar Universiti Awam yang lain . Pelajar USM merupakan pelajar yang paling kekal jati diri mereka dari segi pemahaman, penghayatan dan pengamalan bagi kesemua tujuh konstruk yang dikaji. Implikasi kajian ini adalah bakal guru pelatih di Fakulti Pendidikan, Universiti Awam dan Institut Pendidikan Guru perlu diukur tahap jati diri mereka sebelum diterima masuk dalam progran pendidikan

Efficacy of feed-based adjuvant vaccine against Streptococcus agalactiae in Oreochromis spp. in Malaysia.

This study was conducted to determine the systemic, mucosal immunity and protective capacity of the feed-based adjuvant vaccine (FAV) of Streptococcus agalactiae following oral vaccination against streptococcosis in tilapias. Two hundred and sixteen red tilapia fish were divided into three major groups. Each major group consisted eight tilapia kept in nine 2000 L glass aquaria. At day 0, all fish from the FAV group were fed with feed that had been incorporated with an adjuvant, while fish in the feed-based vaccine (FNV) group were fed with vaccine incorporated into the pellet without adjuvant. Fish in the control-unvaccinated group, FC, were fed with normal commercial pellet. Booster dose was performed on day 14 post immunization. Fish from each group were sacrificed on a weekly basis for the entire 7 weeks. Serum, body mucus and gut lavage fluid were evaluated for antibody responses by indirect ELISA, while histological examination was carried out on the gut following intraperitoneal challenge. The FAV group had a significantly higher protection (P < 0.05) following challenge with 3.4 × 109 CFU mL−1 of live S. agalactiae than FNV group. This level of protection may be due to high antibody responses, increase in size of gut-associated lymphoid tissue and high number of lymphocytes in the FAV grou

Tahap pemahaman, penghayatan dan pengamalan jati diri bahasa Melayu dalam kalangan pelajar aliran pendidikan Universiti Awam

Kajian ini bertujuan mengenal pasti tahap jati diri Bahasa Melayu dalam kalangan 1000 orang pelajar aliran pendidikan di lima buah Universiti Awam bertaraf Universiti Penyelidikan. Secara khsusus, kajian ini bertujuan untuk mengenal pasti tahap pemahaman, penghayatan dan pengamalan jati diri bahasa Melayu pelajar aliran pendidikan tersebut. Setiap Universiti Awam diambil 200 orang sebagai responden kajian. Responden tersebut dipilih secara rawak mudah yang sedang melanjutkan pengajian dalam pelbagai program pendidikan di UKM, UPM, UM, USM dan UTM. Instrumen soal selidik digunakan untuk pengumpulan data. Instrumen dibangunkan oleh pengkaji yang mempunyai tahap kesahan dan kebolehpecayaan yang tinggi, iaitu 0.75. Data dianalisis secara deskriptif dan inferensi menggunakan Statistical Package for Social Sciences (SPSS) versi 23.0. Dapatan kajian menunjukkan bahawa pelajar aliran pendidikan Universiti Awam secara amnya tetap kekalkan jati diri bahasa Melayu mereka. Tahap penghayatan dan pengamalan Bahasa Melayu berada pada tahap masih kekal jati diri. Pelajar UM paling kurang tahap pemahaman, penghayatan dan pengamalan Bahasa Melayu berbanding pelajar Universiti awam yang lain. Pelajar USM pula merupakan pelajar yang paling tinggi tahap jati diri Bahasa Melayu dalam ketiga-tiga aspek yang dikaji. Implikasi kajian ini adalah penekanan kepada penguasaan lisan dan tulisan bahasa Inggeris sedikit oleh pihak universiti sedikit sebanyak mempengaruhi tahap jati diri Bahasa Melayu dari segi pemahaman, penghayatan dan pengamalan bahasa Melayu dalam kalangan pelajar aliran pendidikan Universiti Awam ini

The effects of oral vaccination of Streptococcus agalactiae on stimulating gut-associated lymphoid tissues (GALTs) in tilapia (Oreochromis spp.)

Vaccination of fish by intraperitoneal (i.p.) injection and bath immersion against bacterial infections has been proven to be a commercial success. However, those routes of vaccination are not economical in practice due to several reasons such as high labour cost, highly time consuming, and causing stress to the fish. Meanwhile, oral vaccination is considered as the best route to vaccinate the fish due to less stress to the fish, ability to treat large batch at one time, and easy and practical to administer booster vaccination. In this study, effect of oral vaccination with various regimes in stimulating gut-associated lymphoid tissues (GALTs) against Streptococcus agalactiae infection was observed. In this vaccination experiments, four groups of fish with four replicates consisting of 15 tilapias each were used; four groups per treatment received antigen incorporated vaccine in different regimes. Group 1 was fed with vaccine once per week, Group 2 was fed three consecutive days per week, and Group 3 was fed five consecutive days per week, while Group 4 (control) was fed with standard commercial feed. Booster dose was administered at day-14 after the first administration, and humanely killed at day-28 post-booster vaccination. Ten fish from each group were collected for gut sampling and subjected for histological analysis using Olympus FIVE Image Analyzer. Aggregations of GALTs were observed in lamina propria of the gut. The sizes of GALTs were measured and the numbers of lymphoid cells were also counted. The diameter of GALTs showed no significant (p>0.05) difference between Groups 1 to Group 2 and Group 2 to Group 3, but a significant difference (p0.05) were found between Group 1 to Group 2 and Group 2 to Group 3; however, a significant difference (p<0.05) was observed between Groups 1 and Group 3. As a conclusion, the frequencies of administration play a role in stimulating the size of GALT which is correlated with the number of aggregated lymphoid cells in the gastrointestinal tract of tilapia

Determination of LD50 for Streptococcus agalactiae and Staphylococcus aureus infections in tilapia

One hundred and sixty fingerlings and 80 adult tilapias were experimentally infected with Streptococcus agalactiae and Stapylococcus aureus to determine their LDso. Four concentrations of Streptococcus agalactiae (109, 108,107, 106 CFU/mL) were used in this experimental infection. These tilapias were divided into 4 groups of 40 fingerlings and 20 adults per group. Groups 1, 2, 3 and 4 of the fingerlings were exposed to 109, 10,107, 106 CFU/mL of S. agalactiae by immersion in 2 L inoculum solution for 20 min. Similarly, the adult groups were exposed to the same concentrations of S. agalactiae but by intraperitoneal injection at the rate of 1 mL of the inoculum per gram. Similar procedures were repeated using exposure to Staphylococcus aureus alone or a combination of S. agalactiae and S. aureus. All test groups were observed for signs of infections. On Day 7 post-infection (pi), all fish that were still alive were humanely killed. The LDso of the adult tilapia that were exposed to S. agalactiae, S. aureus or mixed infection was 2.3884 x 107,2.8151 X 108 , and 4.2409 x io', respectively. For the fingerling groups, the LDso for S. agalactiae, S. aureus, and mixed infection was 2.9242 x 1020,2.8665 x 1017 , and 4.9748 x IO!', respectively. Experimental infection in adults could be established within 12 h post-injection to 6.3 x 109 CFU per mL and 9.7 x 109 CFU per mL of S. agalactiae and S. aureus, respectively. For fingerlings, infection could be established within 72 h following bath immersion to 6.3 x 109 CFU per mL and 9.7 x 109 CFU per mL of S. agalactiae and S. aureus, respectively

Passive thermal performance prediction and multi-objective optimization of naturally-ventilated underground shelter in Malaysia

The impact of global warming has urged a prudent spending of energy in the building sector nowadays. In general, a typical HVAC system consumes about 60%e70% of the total energy consumption of a building. Therefore, designing an energy-efficient HVAC system is essential to alleviate the worsening greenhouse effect. Recent research works have reported that geothermal energy coupled with optimal insulation is the best approach in minimising the energy consumption. Thus, we attempted to analyse the thermal performance of a naturally-ventilated underground shelter in a hot and humid country such as Malaysia. We proposed an optimal design to enhance the sustainability of the low-energy building. The model was numerically simulated using CFD, and a statistical surrogate model was implemented for obtaining the optimal design. The findings indicated that the room temperature of the shelter was significantly lower than the outdoor temperature during the hottest month and vice-versa during the coldest month. Moreover, the proposed optimal design showed about 3.4% increase in ventilation rate and about 2.8% decrease in room temperature as compared to the previous design. In general, the current work could be used as a guideline for designing low-energy building in Malaysia