Engineering

Fungsi, status dan kelas jalan sangat penting sesuai dengan ketentuan. Kesesuaian itu akan meminimalkan biaya transportasi maupun biaya pemeliharaan prasarana transportasi, dalam hal ini konstruksi perkerasan jalan, maupun biaya pengguna jalan. Dalam studi ini dilakukan analisis biaya pemeliharaan perkerasan jalan umum yang ditimbulkan oleh kerusakan akibat kendaraan pengangkut hasil tambang mangan. Pada saat perkerasan sudah sesuai dengan ketentuan, kontribusi kendaraan pengangkut hasil tambang terhadap biaya pemeliharaan perkerasan sangat tergantung pada jenis truk dan biaya pemeliharaannya berkisar antara 0,05% - 5,47% dari nilai hasil tambang mangan. Perbedaan biaya pemeliharaan itu selain tergantung pada jenis truk, juga tergantung pada konstruksi perkerasan. Konstruksi perkerasan yang baik dan didesain dengan umur yang lebih panjang, biaya pemeliharaannya lebih murah. Konstribusi kendaraan pengangkut hasil tambang tersebut akan menciptakan struktur perkerasan jalan yang berkelanjutan, karena biaya pemeliharaan yang diperlukan akan tersedia dari dana yang dikontribusi pengguna jalan sendiri.

Selain perencanaan geometric jalan, perkerasan jalan merupakan bagian dari perencanaan jalan yang harus direncanakan secara efektif dan efisien, karena kebutuhan tingkat pelayanan jalan semakin tinggi. Jenis perkerasan jalan W.J. Lalamentik Kota Kupang adalah perkerasan lentur dengan jens lapis permukaan adalah HRS-WC, dimana jalan tersebut sering mengalami kerusakan berulang sebagai akibat dari beban lalulintas dan kondisi lingkungan. Perlu dicoba penggunaan perkerasan kaku untuk diketahui apakah perkerasan tahan sampai pada masa layannya. Terdapat banyak metode untuk mendesain tebal pelat beton ini, diantaranya menggunakan metode Pd T-14-2003 dan AASHTO 1993. Tulisan ini bertujuan untuk menganalisis alternatif desain tebal perkerasan mengkaji pada parameter perencanaan kedua metode, perencanaan tebal pelat beton, dan melakukan analisa perbandingan hasil kedua metode. Metode ini dimulai dengan pengumpulan data sekunder berupa data lalu lintas, data tanah dan data hidrologi, kemudia...

This study investigated the effect of dust to the performance degradation of PV street lights deployed at several areas (coastal, urban, industry, and village) in Kupang city. Results showed that maximum power output (Pmax) of all modules decreased by 9 % to 14 %. Short circuit current (Isc) was the parameter strongly affected by dust compared to open circuit voltage (Voc). Performance of the PV modules increased back to their initial conditions after cleaning. This was indicated by the increasing of Isc and Voc of the modules that leading to the escalating of their Pmax values. The worst effect of dust was exhibited by PV modules installed at coastal area. A simple analysis revealed that the module would lose 87.75 Wh of energy d–1. This study suggested that dust derating factor applied for PV street light design in Kupang should be higher than the standard (5 %).

Secara visual agregat dari lokasi quary Wae Mese dapat dimanfaatkan sebagai agregat untuk campuran beraspal panas maupun untuk campuran beton semen. Setelah dilakukan kajian secara laboratoris material tersebut dapat digunakan sebagai agregat campuran aspal panas AC-WC dengan hasil; memenuhi syarat dari aspek: gradasi agregat (batu pecah 3/4” dan 1/2" sebesar 1,65% dan 1,56%, abu batu dan pasir 9,06% dan 4,89%), berat jenis dan penyerapan air agregat (batu pecah 3/4" dan 1/2" sebesar 1,86% dan 1,50%, abu batu dan pasir 1,48% dan 1,96%) dan abrasi agregat sebesar 23,50%; dan memenuhi Spesifikasi untuk digunakan sebagai material campuran beraspal panas LASTON AC-WC berdasarkan hasil pengujian dan hasil perhitungan parameter Marshall, dengan menggunakan material asal Wae Mese , Kecamatan Watu Nggelek, Kabupaten Manggarai Barat , dengan kadar aspal Optimum 6,25%.

Secara visual agregat dari lokasi quary Wae Mese dapat dimanfaatkan sebagai agregat untuk campuran beraspal panas maupun untuk campuran beton semen. Setelah dilakukan kajian secara laboratoris material tersebut dapat digunakan sebagai agregat campuran aspal panas AC-WC dengan hasil; memenuhi syarat dari aspek: gradasi agregat (batu pecah 3/4” dan 1/2" sebesar 1,65% dan 1,56%, abu batu dan pasir 9,06% dan 4,89%), berat jenis dan penyerapan air agregat (batu pecah 3/4" dan 1/2" sebesar 1,86% dan 1,50%, abu batu dan pasir 1,48% dan 1,96%) dan abrasi agregat sebesar 23,50%; dan memenuhi Spesifikasi untuk digunakan sebagai material campuran beraspal panas LASTON AC-WC berdasarkan hasil pengujian dan hasil perhitungan parameter Marshall, dengan menggunakan material asal Wae Mese , Kecamatan Watu Nggelek, Kabupaten Manggarai Barat , dengan kadar aspal Optimum 6,25%.

Jalan raya merupakan salah satu prasarana yang sangat penting dan sangat dibutuhkan oleh masyarakat karena jalan raya berfungsi menghubungkan sumber–sumber produksi serta berperan  memperlancarkan mobilisasi dan arus transportasi  darat  pada  daerah–daerah sekitarnya yang dapat mempermudah atau mempercepat perkembangan pembangunan baik itu infrastruktur maupun ekonomi suatu daerah. Agar jalan dapat berperan secara optimal, maka jalan harus berada pada keadaan baik, harus memenuhi kriteria konstruksi perkerasan yaitu tidak mudah aus, dan tidak terjadinya perubahan bentuk (Deformasi), sehingga dapat memberikan rasa aman dan nyaman kepada pemakai jalan. Struktur lapis perkerasan  jalan yang sekarang banyak digunakan adalah  struktur lapis perkerasan lentur dengan campuran aspal panas yang disebut Hot Mix, salah satu jenis campuran aspal panas yang digunakan adalah Lataston atau yang lebih di kenal dengan HRS (Hot Rolled Sheet), yang didesain untuk volume lalu-lintas ringan sampai bera...

The "A+B" bid method is determined by the lowest combined bid. Contractors must greatly shorten construction time to be able to win bidding competitions. However, the risk under the shortened duration of construction increased rapidly. For this reason, it is important to propose a bidding strategy to acquire the best composition of construction cost and time. This research targeted contractors with a questionnaire regarding A+B bidding in Taiwan by applied “Utility Function Theory” to construct a decision model of the best construction cost and time. It was found that the optimal profit regressed from the modified utility function differs from contractors’ preliminary bids. In the situation that the difference in basic profits is not large, contractors can set up a decision maker’s utility function based on their ability to take a risk and simulate the major competitors based on experience to judge the potential success and risk from shortening the construction time.

Over the past half-century, value engineering (VE) has emerged as an effective tool to manage time, costs, and quality with an aim to maximize value. It has been shown to be a highly effective approach for evaluating current construction projects. However, this tool’s application in the construction domain is quite variable. This research aims to provide an in-depth quantitative and qualitative content analysis of the application of VE in construction projects. It is found that new research over the past decade has continuously improved the efficiency and productiveness of VE practices. Current work focuses on integrating VE with other disciplines, applying VE in diverse project domains, assessing VE performance, and developing new VE technologies. This broad review highlights some of the key areas of interest that required future investigation to ensure the continued delivery of value in the ever-changing and evolving construction industry.

School buildings and facilities constitute essential educational infrastructure and have a formative impact on the safety, development, and socialization of students. However, many existing school buildings are increasingly aging and deteriorating, requiring urgent refurbishment, raising the need to assess and develop a quality function to propose strategies for improved school building reconstruction. Apart from the initial planning phase, the reconstruction design process usually requires detailed information regarding owner/user demands and is often presented in terms of user dissatisfaction. This paper applies fuzzy quality function deployment (FQFD) to transform actual user needs into an improved technical strategy that can be realized by the design unit through the sequence of the matrix method. The resulting framework identifies a total of eight major components of user dissatisfaction, along with three key school-design improvement strategies, including the use of environmen...

This study investigated the effect of dust to the performance degradation of PV street lights deployed at several areas (coastal, urban, industry, and village) in Kupang city. Results showed that maximum power output (Pmax) of all modules decreased by 9 % to 14 %. Short circuit current (Isc) was the parameter strongly affected by dust compared to open circuit voltage (Voc). Performance of the PV modules increased back to their initial conditions after cleaning. This was indicated by the increasing of Isc and Voc of the modules that leading to the escalating of their Pmax values. The worst effect of dust was exhibited by PV modules installed at coastal area. A simple analysis revealed that the module would lose 87.75 Wh of energy d–1. This study suggested that dust derating factor applied for PV street light design in Kupang should be higher than the standard (5 %).

Transient heat transfer to carbon-film and Pt-foil heater/thermometer devices submerged in LH2 was investigated using a specially designed apparatus, and the conduction and onset of film boiling phases were identified. In the experiments, thin films and Pt foils submerged in liquid hydrogen received stopped power inputs of 1 to 42 W/sq cm, and the onset of nucleate or film boiling was recorded for each power level. The critical heat flux was found to be about 8 W/sq cm, with the transition to film occurring in less than 0.001 sec. It is shown that premature film boiling when using Pt foil heater/thermometers can be related to the narrowness of the heaters (1.524 mm or less) relative to the size of nucleate boiling bubbles, irregularities in the heater material, and a positive coefficient of electrical resistance.

Transient heat transfer to liquid hydrogen was investigated. Then carbon films and Pt foils submerged in liquid hydrogen received stepped inputs of power ranging from 1 to 42 W/sq cm, and the onset of nucleate or film boiling was obtained for each power level. The critical heat flux was found to be approximately 8 W/sq cm, with the transition to

This paper reviews the principles and techniques used in cryogenic refrigeration, with particular emphasis on small cryocoolers. Several thermodynamic cycles used in cryocoolers are discussed, as are the design requirements, applications, and current areas of research. The important features of the Stirling cycle used as a prime mover or refrigerator are compared.

The paper describes the construction and mounting of a small silicon-on-sapphire (SOS) thermometer, a highly sensitive intrinsically fast temperature sensor for measuring transient temperatures in an oscillating cryogenic fluid flow. The SOS sensor is made from a 1-micron-thick silicon layer on a 125-micron-thick sapphire substrate. It has a calculated intrinsic response time of about 10 ns at 4 K, with the sensitivity comparable to Ge or C thermometers in the range of 1-80 K. The large surface area of the SOS thermometer provides good thermal contact with the fluid, while the suspension of the thermometer ensures poor thermal contact with the holder, maintains its fast response time, and withstands high velocities and frequencies of fluid oscillation. A self-heating response time of 300 ns was measured at 4 K in liquid and gaseous helium with repeatability of about 10 mK. Examples of the thermometer performance for He gas oscillations in the frequency range of 1 to 12 kHz are presented, and schematic diagrams are included.

The three types of pulse tube refrigerator, namely the resonant, basic, and orifice designs, are compared with each other and with such common refrigerators as the Joule-Thomson and Stirling types, using an apparatus able to measure their intrinsic behavior from 30 to 300 K. Orifice pulse tubes are found capable of reaching 60 K temperature drops in a single stage. Additional advantages of the type are (1) a single, room-temperature moving part, (2) the use of moderate pressures and pressure ratios, (3) good intrinsic efficiency, and (4) the ability to operate several stages from the same pressure wave generator. The low refrigeration rate/unit mass flow means, however, that better regenerator units are required.

Fe1'(TIM)(C6H5CN)?++ CO 5 Fe11 (TIM)(C6H5CN)(CO) 2++ C6H5CN have been measured in benzonitrile. At 25 OC, Kq= K/[C6H5CN]= kl'/k-,= 420 MI, k,'= 0.14 M-'sI, and k-,= 3.3 X~ O-'S-~. In CO-saturated solutions, the Fe (I1) complex can be oxidized electrochemically by a C, E, E, C, mechanism, which allows the diffusion coefficients of the complex and CO adduct to be determined. The reversible complexation reaction of this Fe (I1) complex with carbon monoxide affords facilitated transport of CO across benzonitrile ...