Computability of Countable Subshifts in One Dimension

We investigate the computability of countable subshifts in one dimension, and their members. Subshifts of Cantor?CBendixson rank two contain only eventually periodic elements. Any rank two subshift in 2^? is decidable. Subshifts of rank three may contain members of arbitrary Turing degree. In contrast, effectively closed ( $\Pi^{0}_{1}$ ) subshifts of rank three contain only computable elements, but $\Pi^{0}_{1}$ subshifts of rank four may contain members of arbitrary $\Delta^{0}_{2}$ degree. There is no subshift of rank ??+1.     

Abrasive Wear of In Situ AlB2/Al-4Cu Composite Material Produced by Squeeze Casting Method

The wear behavior of a weight fraction of particles with up to 30 wt.% in situ AlB₂ flakes reinforced in Al-4Cu matrix alloy composites and fabricated by a squeeze casting method was investigated in a pin-on-disk abrasion test instrument against different SiC abrasives at room conditions. Wear tests were performed under the load of 10 N against SiC abrasive papers of 80, 100, and 120 mesh grits. The effects of sliding speed, AlB₂ flake content, and abrasive grit sizes on the abrasive wear properties of the matrix alloy and composites have been evaluated. The main wear mechanisms were identified using an optical microscope. The results showed that in situ AlB₂ flake reinforcement improved the abrasion resistance against all the abrasives used, and the abrasive wear resistance decreased with an increase in the sliding speed and the abrasive grit size. The wear resistances of the composites were considerably bigger than those of the matrix alloy and increased with increases in in situ AlB₂ flake contents.     

An efficient method for computing cell loss probability for heterogeneous bursty traffic in ATM networks

In this paper, we present an approximation for the probability of cell loss of heterogeneous bursty traffic in broadband integrated packet networks based on the asynchronous transfer mode. The sources considered here alternate between active and silent periods and are characterized by their peak and average transmission rates. The cell loss probability is obtained by considering only the number of active sources at a given time and computing the amount of traffic that exceeds the link capacity. Since the amount of buffered excess traffic is not considered in this computation, this approximation is actually an upper bound of the cell loss probability. The numerical efficiency of this bound enables it to be used as a measure based on which robust and simple resource allocation strategies can be developed for bursty sources. Comparison of this bound with the simulation results has shown that the bound is close to the actual loss probabilities especially for large burst lengths and high utilizations.     

Indoor geolocation in the absence of direct path

Severe multipath in indoor areas causes undetected direct path (UDP) conditions, which pose a serious challenge to the design of robust precision indoor geolocation systems. Based on a scenario on the third floor of the Atwater Kent Laboratory at the Worcester Polytechnic Institute, we explain the reason for frequent absence of direct path, and introduce and analyze the effectiveness of two novel approaches to mitigating the large ranging errors caused by UDP conditions. The first technique exploits nondirect paths for ranging, while the second approach relies on cooperative localization for wireless sensor and ad hoc networks     

Network characterization using constraint-based definitions of capacity, utilization, and efficiency

Capacity planning in an operational network requires continuous monitoring of network resources so that corrective actions can be taken in response to changes in traffic patterns, performance requirements, and network technology. In this article we characterize network resources in terms of capacity, utilization, and efficiency, and define these metrics as functions of the sets of constraints under which the network is operating. These constraints may include service level agreement objectives, routing policy constraints, and failure survivability requirements. Constraint-based network characterization allows a network operator to quantify the inherent capacity of a network and determine the impact of changes in operating conditions on realizable capacity. It also helps assess how well a given network design matches the set of constraints under which it is operating, how much traffic growth the network can support, and what actions need to be taken to accommodate traffic growth.     

Effect of addition of amino acids, treatment with β-galactosidase and use of heat-shocked cultures on the acetaldehyde level in yoghurt

In this study, the biochemical activities of nonviscous and viscous yoghurt starter cultures were investigated. Yoghurt samples produced with nonviscous and viscous cultures, and viscous cultures + methionine (10 and 30 mg/100 mL milk), + threonine (5 and 10 mg/100 mL milk), + β-galactosidase (1 mg/100 mL milk), and with a heat-shocked culture were analysed. In the experimental yoghurts, the pH, titratable acidity, lactic acid, tyrosine and acetaldehyde contents and the number of total starter organisms were determined. According to the results obtained, the samples produced with the viscous culture had the lowest acetaldehyde levels, whereas the highest acetaldehyde level was found in the samples manufactured with the nonviscous culture. Compared with the samples inoculated with the viscous culture alone, the amino acid supplementation, lactose hydrolysis and heat-shock treatments caused a significant increase in the level of acetaldehyde.     

Some properties of urfa cheese (a traditional white-brined Turkish cheese) produced from bovine and ovine milks

In this study, the basic composition and ripening profile of traditional urfa cheese made from ovine and bovine milks were investigated. While cheese made from ovine milk had higher total solids, fat-in-dry matter and total nitrogen, the titratable acidity, salt-in-dry matter, pH, total mesophilic colony count and total yeasts and moulds counts were found to be close to each other. During storage, whilst the total solids content of cheese produced from ovine milk gradually decreased, the variation in the total solids content of cheese made from bovine milk was found to be insignificant. The salt penetration into the cheeses was rapid during the first two weeks of ripening, and it continued to diffuse into the samples throughout storage. Proteolysis developed faster in the cheese made from ovine milk than in cheese of bovine milk. The former sample had higher water soluble nitrogen, nonprotein nitrogen, phosphotungustic acid soluble nitrogen, Proteose-peptone nitrogen and tyrosine levels throughout storage, and the ripening index was higher as well.     

Seismic performance evaluation of slender masonry towers: a case study

Historical structures and preserving their cultural values are crucial issues for humanity, not only because of their link to important certain periods in the past, but also their unique architectural features. Although many historical structures continue to offer services while keeping their historical values, some of them are at high risk in seismic prone regions. Therefore, the understanding of their structural performance under strong ground motions has been of significant importance to the civil societies as well as engineering community. The structural systems of historical buildings, generally, consist of masonry walls or piers. The behavior of such walls is controlled by either deformation or force. Seismic performance evaluation of historical structures can be carried out within the framework of performance‐based evaluation principles. This paper mainly discusses the basic principles to be considered in performance‐based seismic evaluation of historical structures. Proposed seismic hazard levels, evaluation of existing seismic hazard, selection of earthquake ground motions as well as site geology, geological and tectonic settings of the area, seismic activity of the region and local soil conditions are needed for a thorough performance evaluation. Seismic performance evaluation of a clock tower located in eastern Turkey was accomplished based on the proposed principles. Copyright © 2015 John Wiley & Sons, Ltd.     

Next-generation satellite networks: architectures andimplementations

A new generation of satellite networks is being developed to handle highly bursty Internet and multimedia traffic. In these networks, satellite links are used for interconnecting remote network segments as well as for providing direct network access to homes and businesses. In this environment, the satellite network must support not only circuit switched traffic, but also packet services with highly bursty traffic patterns. The traditional circuit switched approach based on the user or network signaling is inadequate to carry dynamically varying packet traffic efficiently, necessitating faster bandwidth allocation solutions. Standard interworking solutions and air interfaces are very important for interoperability leading to proliferation of satellite networks to potentially millions of home and business users. In this article we provide an overview of the standardization effort that has started at the TIA in the area of satellite ATM networks. Subsequently, a bandwidth-on-demand multiservice satellite network architecture implementation is described     

Changes of composition and free fatty acid contents of Urfa cheeses (a white-brined Turkish cheese) during ripening: Effects of heat treatments and starter cultures

The influences of heat treatments (at 65 °C for 20 min or 72 °C for 5 min) applied to the milk and addition of mesophilic or thermophilic starter cultures, prior to cheese-making, on the composition and free fatty acid contents of Urfa cheeses were evaluated throughout the ripening period. Sensory evaluation of cheese samples was also performed on 90th day. The basic composition of ripened cheese samples was not significantly affected by the heat treatments and starter cultures. Heat treatments adversely affected the lipolysis and sensory properties of Urfa cheeses, particularly at 72 °C. The FFA contents of cheeses made from mesophilic and thermophilic cultures were similar. Cheese made from raw milk had a higher level of lipolysis than the cheeses made from milk inoculated with mesophilic or thermophilic lactic starters (p < 0.05).