Integrated voice/data protocols for satellite channels

Several integrated voice/data protocols for satellite channels are studied. The system consists of two types of traffic: voice calls which are blocked-calls-cleared and the data packets which may be stored when no channel is available. The voice calls are operated under a demand assignment protocol. Three different data protocols for data packets are introduced. Under Random Access Data (RAD), the Aloha random access scheme is used. Due to the nature of random access, the channel utilization is low. Under Demand Assignment Data (DAD), a demand assignment protocol is used to improve channel utilization. Since a satellite channel has long propagation delay, DAD may perform worse than RAD. The two protocols are combined to obtain a new protocol called Hybrid Data (HD). The proposed protocols are fully distributed and no central controller is required. Numerical results show that HD enjoys a lower delay than DAD and provides a much higher channel capacity than RAD. The effects of fixed and movable boundaries are compared in partitioning the total frequency band to voice and data users

Preliminary study of microtektites first discovered in the central Pacific by China

Electron probe analysis was used to determine the chemical composition of microtektites discovered in the Central Pacific. An X-ray energy spectrum analysis was made, and the surface microstructure was investigated. The found microtektites appear to be younger than the microtektites reported in the Asia Australia Strewn Field

Detection of reflector surface error from near-field data: Effect of edge diffracted field

The surface accuracy of large reflector antennas must be maintained within certain tolerances if high gain/low sidelobe performance is to be achieved. Thus the measurement of the surface profile is an important part of the quality control procedure when constructing antennas of this type. An efficient method for surface profile measurement has been proposed, i.e., the reflector surface is calculated from the measured near-field phase data using the theory of geometric optics. For a surface profile calculation of this kind, it is necessary to know the margin of error built into the method of calculation. This will enable a specification of the tolerance from which the surface profile can be determined. When calculating the surface profile from near-field phase data, there are two main sources of error. The first is the measurement error in near-field phase data. The second arises from the edge diffracted fields that are superimposed on the reflected fields in the measured near-field data. The error in the calculated surface profile produced by the edge diffracted fields is examined

Measurement of fast-time heatflux with inverse thermoacoustic algorithms

Based on the heat-to-sound and virtual-source principles developed in previous works, this paper designs a thermoacoustic traducer for measurement of fast-time heatflux from/to heating/cooling sources. The inverse thermoacoustic algorithm in this instrumentation is fulfilled by a PID-adaptive Luenberger observer, which is newly developed here. It is able to real-time measure the heatflux with oscillating frequency larger than 10 Hz, beyond the capability of thermoelectric sensors. Such an elegant performance is then utilized to clarify the following two doubts: one is about the ad hoc energy-transfer process in self-excited thermoacoustics, and the other is for the existence of thermal-inductance materials in natur

Geochemical Investigation of the Lower Cuyahoga River, Cleveland, Ohio

Author Institution: Department of Geology, Cleveland State UniversityFifty-four surface and near-bottom water samples from the lower Cuyahoga River were collected in the early spring of 1974. The distribution of K, Na, Ca, Mg and Zn with respect to water depth and location in the river was investigated. The average concentrations of K, Na, and Zn of the surface samples are slightly higher than those of the near-bottom samples. Correlation between element concentration and distance along the river indicates that Mg stays nearly constant and other elements fluctuate, particularly along the sections with local industries. The sharp drop of K and Na contents in near-bottom samples near the river's mouth could be caused by the intrusion of cooler lake water. pH values of water samples were slightly alkaline, ranging from 6.98 to 7.45. The average concentrations of K, Na, Ca, Mg, and Zn of the lower Cuyahoga River were 6.2, 60.8, 58.2, 15.0, and 0.020 ppm respectively. These values are considerably higher than those of the mid-lake water of Lake Erie

Perspectives on a 2019 Tiger-Human Interaction Incident in Malaysia

This article describes a 2019 incident in Malaysia in which two tigers were seen near a village. After providing context on the situation of tigers internationally and in Malaysia, the article reports an ecolinguistic study of 10 online articles on the incident from established media sources. Categories used in analyzing the articles were human concern for tigers, tigers owned by humans, tigers provoking fear, animals for human entertainment, tigers as criminals, use of pronouns to refer to tigers, and provision of background on the situation of tigers in Malaysia. The analysis found that the online articles reflected a human-centric perspective. This perspective contrasts with a humans-as-fellow-animals view. The latter view is supported by cited studies of people’s perspective in rural India and of the status of a wide variety of nonhuman animals as thinking, feeling beings. Recommendations are made that the adoption of a humans-as-fellow-animals perspective may be important to the welfare and continued existence in the wild of tigers and other endangered species.Este artigo descreve um incidente em 2019 na Malásia, no qual dois tigres foram vistos próximos a uma aldeia. Após apresentar o contexto sobre a situação dos tigres em nível internacional e na Malásia, o artigo apresenta um estudo de 10 artigos online sobre o incidente na mídia. As categorias usadas na análise dos artigos foram preocupação humana com os tigres, tigres de propriedade de humanos, tigres provocando medo, animais para diversão humana, tigres como criminosos, uso de pronomes para se referir aos tigres e apresentação do contexto dos tigres na Malásia. A análise mostrou que os artigos online refletiam uma perspectiva humano-cêntrica, que contrasta com a visão de humanos-como-parceiros-animais. Essa última visão é comparada a estudos mencionados sobre a perspectiva das pessoas na Índia rural e ao status de uma variedade de animais não humanos como pensantes, sencientes. Sugere-se que a adoção de uma perspectiva humanos-como-parceiros-animais pode ser importante para o bem-estar e continuidade da existência de tigres em estado selvagem, bem como a de outras espécies