Enhancement of height system for Malaysia using space technology: the study of the datum bias inconsistencies in Peninsular Malaysia

The algorithm for orthometric height transfer using GPS has been widely presented. Its practical limitations are mostly due to datum bias inconsistencies and lack of precise geoid. In most applications, datum biases are assumed to be systematic over short baselines and therefore could be eliminated by differential heighting techniques. In this study, optimal algorithms were investigated to model biases between local vertical datum in Peninsular Malaysia and the datums implied by by EGM96, OSU91A and the regional Gravimetric Geoid in South_East Asia. The study has indicated that local vertical datum is not physically parallel to the datums implied by the above geoids. The shift parameters between the datums implied by the GPS/leveling data, and the EGM96, OSU91A and the gravimetric datums are about – 41cm, -54 cm and – 8 cm respectively. Also the maximum tilts of the planes fitting the residual geoids above these datums relative to GPS/Leveling datum are of the order of 36, 51 and 33 centimeters per degree. It is therefore necessary to take into account the effect of inconsistent datum bias particularly for baseline height transfer. The level of accuracy achieved by the bias corrected relative orthometric height differences of the EGM96, OSU91A and the gravimetric geoid models combined with GPS/leveling data for baseline lengths up to 36 km, is sufficient to replace the conventional tedious, time consuming ordinary leveling technique for rapid height transfer for land surveying and engineering applications

Sea level change in the Malaysian seas from multi-satellite altimeter data

Seas from satellite altimetry data of the Topex, Jason-1, ERS-1, ERS-2 and Envisat missions. During the past two decades, satellite altimeter has provided its capability in measuring the global mean of sea level with precision better than 1 mm/year. Sea level data retrieval and reduction were carried out using Radar Altimeter Database System (RADS). In RADS data processing, the recently updated environmental and geophysical corrections were applied. Sixth 1° × 1° areas were chosen for the altimeter data comparison and to find the best ocean tide model for Malaysian Seas, where the altimeter tracks are nearby to tide gauge locations. Similarity in the pattern of sea level variations indicated good agreements between tide gauge data and altimeter data using FES2004 ocean tide model. It also showed that the altimeter data can be used to investigate sea level rise for Malaysian Seas. Here, sea level variations for four areas in the Malaysian Seas have been investigated using 15 years of altimeter data. The altimeter sea level time series revealed that since 1993, the mean sea level in Malaysian Seas has been rising at a rate of between 1.42 – 4.08 mm/year. This information is important to study alternative energy extraction and environmental issues related to flood investigations and global warming

Surveillance Evaluation of the National Cancer Registry in Sabah, Malaysia

Background: Cancer is the fourth leading cause of death in Sabah Malaysia with a reported age-standardized incidence rate was 104.9 per 100,000 in 2007. The incidence rate depends on non-mandatory notification in the registry. Under-reporting will provide the false picture of cancer control program effectiveness. The present study was to evaluate the performance of the cancer registry system in terms of representativeness, data quality, simplicity, acceptability and timeliness and provision of recommendations for improvement. Materials and Methods: The evaluation was conducted among key informants in the National Cancer Registry (NCR) and reporting facilities from Feb-May 2012 and was based on US CDC guidelines. Representativeness was assessed by matching cancer case in the Health Information System (HIS) and state pathology records with those in NCR. Data quality was measured through case finding and re-abstracting of medical records by independent auditors. The re-abstracting portion comprised 15 data items. Self-administered questionnaires were used to assess simplicity and acceptability. Timeliness was measured from date of diagnosis to date of notification received and data dissemination. Results: Of 4613 cancer cases reported in HIS, 83.3% were matched with cancer registry. In the state pathology centre, 99.8% was notified to registry. Duplication of notification was 3%. Data completeness calculated for 104 samples was 63.4%. Registrars perceived simplicity in coding diagnosis as moderate. Notification process was moderately acceptable. Median duration of interval 1 was 5.7 months. Conclusions: The performances of registry’s attributes are fairly positive in terms of simplicity, case reporting sensitivity, and predictive value positive. It is moderately acceptable, data completeness and inflexible. The usefulness of registry is the area of concern to achieve registry objectives. Timeliness of reporting is within international standard, whereas timeliness to data dissemination was longer up to 4 years. Integration between existing HIS and national registration department will improve data quality

Fabrication of high performance PVDF hollow fiber membrane using less toxic solvent at different additive loading and air gap

Existing toxic solvents in the manufacturing of polymeric membranes have been raising concerns due to the risks of exposure to health and the environment. Furthermore, the lower tensile strength of the membrane renders these membranes unable to endure greater pressure during water treatment. To sustain a healthier ecosystem, fabrication of polyvinylidene fluoride (PVDF) hollow fiber membrane using a less toxic solvent, triethyl phosphate (TEP), with a lower molecular weight polyethylene glycol (PEG 400) (0–3 wt.%) additive were experimentally demonstrated via a phase inversion-based spinning technique at various air gap (10, 20 and 30 cm). Membrane with 2 wt.% of PEG 400 exhibited the desired ultrafiltration asymmetric morphology, while 3 wt.% PEG 400 resulting microfiltration. The surface roughness, porosity, and water flux performance increased as the loading of PEG 400 increased. The mechanical properties and contact angle of the fabricated membrane were influenced by the air gap where 20 cm indicate 2.91 MPa and 84.72◦, respectively, leading to a stronger tensile and hydrophilicity surface. Lower toxicity TEP as a solvent helped in increasing the tensile properties of the membrane as well as producing an eco-friendly membrane towards creating a sustainable environment. The comprehensive investigation in this study may present a novel composition for the robust structure of polymeric hollow fiber membrane that is suitable in membrane technology

Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control

Dengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however, the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates

Spatial distribution and long-term persistence of Wolbachia-infected Aedes aegypti in the Mentari Court, Malaysia

Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme

Almanak ukur Malaysia

Alamanak Ukur Malaysia (AUM) telah dihitung oleh Pejabat Almanak, Fakulti Ukur, Universiti Teknologi Malaysia. Perhitungannya adalah diasaskan kepada teori-teori asas pergerakan planet dan tidak ada data yang diambil secara langsung daripada mana-mana almanak yang sedia ada. Ketepatan data-data yang terdapat di dalam Star Almanac for Surveyors (SAS). Argumen masa yang digunakan di dalam AUM adalah Waktu Piawai Malaysia (WPM) bersamaan UT +8jam. Ini secara langsung membezakan nilai-nilai yang dijadualkan oleh AUM daripada yang terdapat di SAS

The Malaysian seas: variation of sea level observed by tide gauges and satellite altimetry

Since a decade, satellite altimetry has demonstrated its capability in measuring temporal change of the global mean sea level with precision better than 1 mm/year. In altimetry data processing, the recently updated environmental and geophysical corrections were applied. The analysis of Topex data presented here is based on monthly averages using GOT00.2b ocean tide model. Sea level trends are estimated from 1.5 to 8.9 mm/year using two decades of tide gauges observations along coastal of Malaysia. Comparison of 1o x 1o areas at the tide gauge locations nearby Topex track clearly show good agreement in pattern and trend of sea level variations. Here, sea level variations for four areas in the Malaysian Seas have been investigated using ten years of Topex altimetry data. The time series of dynamic sea surface elevation clearly show El Nino effect on the end of 1997 and sea level rising in the Malaysian Seas. Linear terms of sea level variation for those areas are estimated at rates between 6.3-14.7 mm/year

Study of sea level variation of exclusive economic zone of Malaysia

Since a decade, satellite altimetry has demonstrated its capability in measuring temporal change of the global mean sea level with a precision better than 1 mm/year. Here, sea level variation for four areas in Exclusive Economic Zone (EEZ) of Malaysia have been investigated using eleven years of Topex altimetry data. The recently updated environmental and geophysical corrections were applied in altimetry data processing. The analysis of Topex data presented is based on cycle by cycle averages using GOT00.2b and FES2002 ocean tide model. The time series of dynamic sea surface elevation clearly show El Niño effect on the end of 1997 and sea level rising in EEZ of Malaysia. Linear term of sea level variation for those areas are estimated at a rate between 2.5 – 8.8 mm/year. Comparison results between two ocean tide present that GOT00.2b better than FES2002 for shallow water such as Malacca Strait

Study towards real time precise point positioning systems using GPS engine receiver

Since the Selective Availability ( SA ) was set to zero, the point positioning becomes an interesting field of study. The precise single point positioning using single frequency GPS receiver is one of the challenging researches. This study was to initial study towards development of the precise single point position solution with accuracy better than 2 m using a low cost single frequency GPS receiver. The positioning algorithm was written in Mailab170 and it incorporates all the significant errors and bias. The significant errors and bias are satellite clock errors, receiver clock errors, tropospheric and ionospheric bias, relativistic effect, earth rotation effect, and satellite antenna phase center offset. Some simulations were performed to validate the result. The results of the study showed significant improvements in accuracy after the SA was set to zero and this fits to the statement of the White House USA that the accuracy will be ten times better than before. The findings suggest that it could be enhanced for better accuracy and integrated in a single built system of hardware and software for further and higher investigations as a low cost commercial GPS equipment