Mechanism of saline deposition and surface flashover on high-voltage insulators near shoreline:mathematical models and experimental validations

This paper deals with sea salt transportation and deposition mechanisms and discusses the serious issue of degradation of outdoor insulators resulting from various environmental stresses and severe saline contaminant accumulation near the shoreline. The deterioration rate of outdoor insulators near the shoreline depends on the concentration of saline in the atmosphere, the influence of wind speed on the production of saline water droplets, moisture diffusion and saline penetration on the insulator surface. This paper consists of three parts: first a model of saline transportation and deposition, as well as saline penetration and moisture diffusion on outdoor insulators, is presented; second, dry-band initiation and formation modelling and characterization under various types of contamination distribution are proposed; finally, modelling of dry-band arcing validated by experimental investigation was carried out. The tests were performed on a rectangular surface of silicone rubber specimens (12 cm × 4 cm × 8 cm). The visualization of the dry-band formation and arcing was performed by an infrared camera. The experimental results show that the surface strength and arc length mainly depend upon the leakage distance and contamination distribution. Therefore, the model can be used to investigate insulator flashover near coastal areas and for mitigating saline flashover incidents.</p

Residential energy demand in Australia: an application of dynamic OLS

This paper reports estimates of the long-run elasticities of residential demand for electricity, natural gas and other fuels for Australia. The dynamic OLS (DOLS) framework is used to estimate logarithmic demand equations with previously unpublished national-level quarterly data. Significant substitution possibilities are found between electricity and gas and between electricity and other fuels. However, the cross-price elasticity of gas with respect to the price of residual fuels is negative. Our results are similar to other Australian and North American estimates but are more theoretically consistent than previous Australian estimates. We confirm that Australian residential energy demand is much more price responsive than North American residential energy demand.

The structure of Australian residential energy demand

This paper presents the first national-level econometric estimates of the residential energy demand system for Australia. We estimate an Almost Ideal (AI) demand system for electricity, gas, and other miscellaneous fuels (mainly oil and wood) using quarterly data for both the country as a whole and for a panel of the five most populous States. The national data set covers the period from 1969 Q3 to 1998 Q2, while the state level data is only available from 1984 Q3 onwards. According to the national-level data, the pairs of electricity and miscellaneous fuels and gas and miscellaneous fuels are significant substitutes, whereas electricity and gas - the two main fuels - may be complements. The panel model, in contrast, finds significant substitution possibilities between gas and miscellaneous fuels only. The cross-price elasticities between electricity and gas are positive but not significant. The gas own-price elasticity is zero in the national model and unit elastic in the panel model. A national model estimated over the same shorter time period still shows complementarity between electricity and natural gas but most results are insignificant. Both large time-series and cross-sectional dimensions are valuable in estimating elasticities. Compared to North American estimates, our results show greater own price and income elasticities for natural gas and the miscellaneous category. They also show more substitutability between natural gas and the miscellaneous category.

The Structure of Australian Residential Energy Demand

This paper presents the first national-level econometric estimates of the residential energy demand system for Australia. We estimate an Almost Ideal (AI) demand system for electricity, gas, and other miscellaneous fuels (mainly oil and wood) using quarterly data for both the country as a whole and for a panel of the five most populous States. The national data set covers the period from 1969 Q3 to 1998 Q2, while the state level data is only available from 1984 Q3 onwards. According to the national-level data, the pairs of electricity and miscellaneous fuels and gas and miscellaneous fuels are significant substitutes, whereas electricity and gas - the two main fuels - may be complements. The panel model, in contrast, finds significant substitution possibilities between gas and miscellaneous fuels only. The cross-price elasticities between electricity and gas are positive but not significant. The gas own-price elasticity is zero in the national model and unit elastic in the panel model. A national model estimated over the same shorter time period still shows complementarity between electricity and natural gas but most results are insignificant. Both large time-series and cross-sectional dimensions are valuable in estimating elasticities. Compared to North American estimates, our results show greater own price and income elasticities for natural gas and the miscellaneous category. They also show more substitutability between natural gas and the miscellaneous category

Residential Energy Demand in Australia: an Application of Dynamic OLS

This paper reports estimates of the long-run elasticities of residential demand for electricity, natural gas and other fuels for Australia. The dynamic OLS (DOLS) framework is used to estimate logarithmic demand equations with previously unpublished national-level quarterly data. Significant substitution possibilities are found between electricity and gas and between electricity and other fuels. However, the cross-price elasticity of gas with respect to the price of residual fuels is negative. Our results are similar to other Australian and North American estimates but are more theoretically consistent than previous Australian estimates. We confirm that Australian residential energy demand is much more price responsive than North American residential energy demand

PENGARUH TEKNIK MODULASI TERHADAP KINERJA LAYANAN VOICE DAN VIDEO PADA JARINGAN WIMAX MENGGUNAKAN OPNET MODELER

Kestabilan jaringan WiMAX dapat dinilai dari quality of service (QoS), pada saat koneksi dengan internet memerlukan bandwith yang memadai terutama pada layanan voice dan video. Quality of service untuk layanan voice dan video merupakan permasalahan komunikasi internet secara keseluruhan. Salah satu cara untuk menjaga kestabilan kualitas layanan yaitu menggunakan teknik modulasi, dimana teknik modulasi memungkinkan pengaturan pola sinyal modulasi yang tergantung pada kondisi signal to noise ratio (SNR). Penelitian ini membandingkan tipe modulasi QPSK, 16QAM dan 64QAM. Hasil pengujian didapatkan perbandingan nilai delay, throughput, Block error rate (BLER) dan signal to noise ratio (SNR) pada masing-masing modulasi tersebut.Kata Kunci : WiMAX, modulasi, voice, vide

A Dynamic Model of Milk Production Response for Pakistan

Economists have long been analysing the determinants of milk production while focusing on the relationship between milk price and production. Brandow (1953) used a single equation regression procedure to estimate the supply response function for the United States. Halvorson (1955) also used a single equation regression .procedure to analyse the determinants of milk production per cow and found milk production to be highly price inelastic. In another study, Halvorson (1958) used the Nerlovian distributed lag model to estimate both short-run and long-run price elasticities of milk production. Here, he found the long-run price elasticities of United States milk production to be in the range of 0.30 to 0.50. Chen et af. (1972) estimated milk production response for both a polynomial and a geometrically declining distributed lag price structure. They found long-run price elasticity to be 2.53. Buckwell (1982) adapted a theory of farm size demonstrated by Kislev and Peterson (1982) to model milk production behaviour in England and Wales. Burton (1984) used a model of the United Kingdom dairy sector to determine simultaneously herd size, number of culls, replacement heifer price, and milk price. In a recent study, Chavas and Kraus (1990) developed a dynamic model of a dairy cow population and milk supply response and applied it to the US Lake States. The authors also calculated dynamic supply elasticities and found the response of supply to market prices to be very inelastic in the short run

Design and implementation of hybrid vehicle using control of DC electric motor

The electric motors and its control technology are key components of hybrid electric vehicles (HEVs). Control of the electric motor is a fundamental issue for traction application in electric vehicles and HEVs. This paper presents the design, development and implementation of a hybrid vehicle using both an electric motor and petrol engine to increase efficiency and decrease carbon footprint. Initially, a prototype of a HEV is designed and the performance values are calculated, before a control system is developed and implemented to control the DC motor speed using a microcontroller as the vehicle’s electronic control unit along with simple proportional integral derivative (PID) control using speed as a feedback mechanism. The prototype made incorporated voltage, current, speed and torque sensors for feedback resulting in a closed loop control system which successfully matched the speed input of a user-controlled pedal sensor. A user interface was developed to show the driver of the vehicle key variables such as the revolutions per minute (RPM) of the motor, the speed of the vehicle along with the current being drawn, and the voltage applied to the motor with overall power. To output a variable voltage from the Arduino, a digital output was used with pulse width modulation (PWM) capabilities in order to provide a variable DC voltage to the speed controller

Penggunaan Media Sosial Secara Lestari di Kalangan Pustakawan (Sustainable Use of Social Media Among Librarians)

There are many research studies that provide recommendations for the libraries to be active in social media. This showed that social media is the important modern communication application for spread-widely the promotion of library services to local and international communities. However, how about the importance of using social media in order to increase the positive perception towards the librarian profession?. Furthermore, Why are there needs for a librarian to utilize the social media sustainably? This is an article all about/Terdapat banyak kajian penyelidikan yang memberi saranan kepada Perpustakaan untuk aktif di media sosial. Hal ini menunjukkan bahawa media sosial merupakan aplikasi komunikasi moden yang penting untuk menghebah luas perkhidmatan Perpustakaan kepada masyarakat tempatan dan antarabangsa. Namun, bagaimana pula kepentingan media sosial dalam meningkatkan persepsi positif masyarakat terhadap kerjaya Pustakawan?. Tambahan pula, Mengapakah wujud keperluan seseorang Pustakawan memanfaatkan penggunaan media sosial secara lestari? Hal inilah yang cuba dikupas dalam artikel ini