Scalable Overlay Multicast Tree Construction for QoS-Constrained Media Streaming

Overlay networks have become popular in recent times for content distribution and end-system multicasting of media streams. In the latter case, the motivation is based on the lack of widespread deployment of IP multicast and the ability to perform end-host processing. However, constructing routes between various end-hosts, so that data can be streamed from content publishers to many thousands of subscribers, each having their own QoS constraints, is still a challenging problem. First, any routes between end-hosts using trees built on top of overlay networks can increase stress on the underlying physical network, due to multiple instances of the same data traversing a given physical link. Second, because overlay routes between end-hosts may traverse physical network links more than once, they increase the end-to-end latency compared to IP-level routing. Third, algorithms for constructing efficient, large-scale trees that reduce link stress and latency are typically more complex. This paper therefore compares various methods to construct multicast trees between end-systems, that vary in terms of implementation costs and their ability to support per-subscriber QoS constraints. We describe several algorithms that make trade-offs between algorithmic complexity, physical link stress and latency. While no algorithm is best in all three cases we show how it is possible to efficiently build trees for several thousand subscribers with latencies within a factor of two of the optimal, and link stresses comparable to, or better than, existing technologies

The Study Committee and the Community

A community study committee will undergo change in knowledge, feelings, thinking and enthusiasm as it explores a community problem. When the time arrives for the committee's report and recommendations, there may be a gap between the knowledge, thinking, feelings and enthusiasm of the committee and that of the citizens and appointing body.Reviewed October 1993.Includes bibliographical reference

Developing Effective Study Committees

Study committees can generate considerable enthusiasm with recommendations that will help solve the community's problems. They can develop a "group spirit" that carries over into the community. This "group togetherness" is greatly influenced by methods study committees use. While there is no one way of achieving a "group spirit," there are known factors that influence its development.Reviewed October 1993

Working With Resource People

Resource people can and should play a vital role in changing communities. City governments, community institutions, organizations and groups are often confronted with issues that make special knowledge and assistance a must in forming intelligent decisions.Reviewed October 1993.Includes bibliographical reference

The Heidelberg Basin drilling project: Geophysical pre-site surveys

Das Heidelberger Becken wird aktuell durch neue Kernbohrungen untersucht, um das Wissen hinsichtlich der Steuerung der pliozänen und quartären Sedimentation durch Klima und (Neo)Tektonik zu erweitern. Es wird erwartet, dass das Heidelberger Becken eine Schlüsselstelle für eine verbesserte Korrelation von Parametern darstellt, welche die Klimaentwicklung in Nordeuropa und im alpinen Raum charakterisieren. Besondere Bedeutung hat daher die Gewinnung von Sedimentsukzessionen hoher zeitlicher Auflösung, die im Hinblick auf die Ablagerung kalt- und warmzeitlicher pleistozäner Sedimente in Superposition möglichst vollständig sind. Im Vorfeld der neuen Kernbohrungen bei Viernheim und Heidelberg wurden geophysikalische Vorerkundungen durchgeführt, um Bohrlokationen zu identifizieren, die diesen Ansprüchen am besten genügen. Im Bereich Heidelberg wird die größte negative Schwereanomalie des gesamten Oberrheingrabens beobachtet (mit Ausnahme der Alpen), was auf ungewöhnlich mächtige Sedimentablagerungen hindeutet. Aber insbesondere reflexionsseismische Messungen haben zur Auswahl der Bohrpunkte beigetragen. Im Stadtbereich von Heidelberg ist zum ersten Mal das Depozentrum des Heidelberger Beckens kartiert worden, abgebildet durch eine zusätzliche Absenkung gegenüber der Umgebung. In diesem Gebiet fallen die Sedimente zum Östlichen Grabenrand hin ein. Dies wird als ‘Rollover’ Struktur interpretiert, die in Verbindung mit der maximalen Subsidenz des Oberrheingrabens in diesem Bereich steht. An der Bohrlokation Viernheim konnten durch die Seismik zahlreiche Störungen abgebildet werden. Obwohl diese im Wesentlichen auf Tiefenbereiche größer 225 m beschränkt sind, wurde der Bohransatzpunkt schließlich aufgrund dieser Informationen gewählt.researc

Balancing Of Chemical Equations Using Matrix Algebra.

This study describes a procedure employing Gaussian elimination method in matrix algebra to balance chemical equations from easy to relatively complex chemical reactions. The result shows that 2 atom of sodium (Na), 6 atoms of oxygen (O), 4 atoms of Hydrogen (H), and 1 atom of sulfur (S) each on both the reactants and products  makes the chemical equation balance. This result satisfies the law of conservation of matter and confirms that there is no contradiction to the existing way(s) of balancing chemical equations. Keywords: Balanced equation, Conservation of matters, Reactants, Products, Matrixes

VALUASI EKONOMI WISATA PANTAI MATAKUS KECAMATAN TANIMBAR SELATAN

The Matakus Beach is located in the Village of Matakus, South Tanimbar Subdistrict, Tanimbar Islands Regency (KKT), Maluku Province. This beach is situated on a small island with a total area of about 474 hectares and a circumference of 9,972 meters. Consequently, Matakus Island has promising prospects for development into an island tourism destination, necessitating an economic valuation. This research aims to determine the influence of travel costs to Matakus Beach on the interest to revisit, analyze the factors affecting the number of visits to Matakus Beach, and assess the economic value of Matakus Beach tourism. The basic research methods employed include survey, literature review methods and the data analysis is quantitative. The research findings indicate that the general characteristics of respondents show that tourists are predominantly aged 27-36 year with an average income of Rp 4.08 million per month. The results show travel costs amounting to Rp 32,615,000 per month. The analysis indicates that the variable with a significant relationship to the number of tourist visits is the travel cost variable, with a significance value of 0.004 smaller than 0.05 (0.004 <0.05), meaning that the number of tourist visits is mutually influenced by travel costs. The coefficient of determination (R²) is 0.624, indicating an independent variability of 62.4%. The economic value of Matakus Beach tourism is calculated at Rp 178,412,140 per month

Geostatistical mapping of the depth to the bottom of magnetic sources and heat flow estimations in Mexico

The depth to the bottom of magnetic sources (DBMS) is widely used as a proxy for crustal thermal structures. In this study, the DBMS is calculated using the spectral analysis of aeromagnetic data for the whole territory of Mexico. By assuming the DBMS to be related to the Curie point depth, the heat flow distribution is estimated. The DBMS and heat flow maps were constructed using geostatistical simulations to quantitatively determine standard deviation as uncertainty. The results show a good agreement with the complex geologic and tectonic setting in Mexico. Small DBMS values (high heat flow) as expected appear in areas where recent volcanism occurs and at seafloor spreading zones. In contrast, large values are present in tectonically stable zones

Cuspate-lobate folding in glacial sediments revealed by a small-scale 3-D seismic survey

We carried out a small-scale 3-D seismic survey (120 × 120 m2, bin size 1.5 m) in advance of a research borehole. The target consists of 150 m of Quaternary sediments in a glacially overdeepened valley. We used a wheelbarrow-mounted electrodynamic vibrator as seismic source and chose a simple orthogonal layout. During one week of acquisition, we fired 1024 shots into 384 vertical geophones. The key processing step was the interpolation and regularization of traces, realized by common reflection surface (CRS) processing. This enhances data quality in low fold regions at small offsets. Despite the small source, the entire Quaternary fill and the base of the valley is imaged well. At a depth of 20–50 m, glaciotectonic deformation, in the form of cuspate-lobate folds, is visible, which was not recognized previously in a 2-D seismic profile that runs along the edge of the 3-D area. The folding indicates that compressional glacial stresses acted on layers of stiff till and less competent clastics. We interpret that the varying fold axes' directions indicate varying stress fields during the Last Glacial Maximum. Cuspate-lobate folding has hitherto not been used to describe the deformation of glacial sediments

Geodetic monitoring of subrosion-induced subsidence processes in urban areas: Concept and status report

The research project SIMULTAN applies an advanced combination of geophysical, geodetic, and modelling techniques to gain a better understanding of the evolution and characteristics of sinkholes. Sinkholes are inherently related to surface deformation and, thus, of increasing societal relevance, especially in dense populated urban areas. One work package of SIMULTAN investigates an integrated approach to monitor sinkhole-related mass translations and surface deformations induced by salt dissolution. Datasets from identical and adjacent points are used for a consistent combination of geodetic and geophysical techniques. Monitoring networks are established in Hamburg and Bad Frankenhausen (Thuringia). Levelling surveys indicate subsidence rates of about 4-5 mm per year in the main subsidence areas of Bad Frankenhausen with a local maximum of 10 mm per year around the leaning church tower. Here, the concept of combining geodetic and gravimetric techniques to monitor and characterise geological processes on and below the Earth's surface is exemplary discussed for the focus area Bad Frankenhausen. For the different methods (levelling, GNSS, relative/absolute gravimetry) stable network results at identical points are obtained by the first campaigns, i.e., the results are generally in agreement. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017