Some studies on the behavior of W-RE thermocouple materials at high temperatures

Bare 0.25 mm diameter W-Re alloy thermoelements (W, W-3% Re, W-5% Re and W-25%) and BeO-insulated W-3% Re and W-25% Re thermoelements were examined for metallurgical, chemical and thermal emf changes after testing for periods up to 1000 hours at temperatures principally in the range 2000 to 2400 K. Environments for the tests consisted of high purity argon, hydrogen, helium or nitrogen gases. Commercially obtained bare-wire thermoelements typically exhibited a shift in their emf-temperature relationship upon initial exposure. The shift was completed by thermally aging the W-3% Re thermoelement for 1 hour and the W-25% Re thermoelement for 2 minutes at 2400 K in argon or hydrogen. Aged thermoelements experienced no appreciable drift with subsequent exposure at 2400 K in the gaseous environments. The chemically doped W3% Re thermoelement retained a small-grained structure for exposure in excess of 50 hours at 2400 K. BeO-insulated thermoelement assemblies showed varied behavior that depended upon the method of exposure. However, when the assemblies were heated in a furnace, no serious material incompatibility problems were found if the materials were given prior thermal treatments. Thermocouples, assembled from aged W-3% Re and W-25% Re thermoelements and degassed sintered BeO insulators, exhibited a drift of only 2 to 3 K during exposure in argon at 2070 K for 1029 hours

An investigation of W-3% Re and W-25% Re thermoelements in vacuum, argon and hydrogen Final report

High vacuum, argon, and hydrogen effects on bare wire rhenium thermoelements at high temperature

Nonlinear phononic crystals based on chains of disks alternating with toroidal structures

We study experimentally the acoustic response of a load-bearing, phononic crystal composed of alternating steel disks, and polytetrafluoroethylene o-rings under precompression. The crystal allows for axial, rocking, and shear-polarized wavemodes when excited by a broad-band signal applied off-axis. Finite element analysis is employed to determine the system’s wave modes. The nonlinear interaction between disks and o-rings supports a dynamic response that is tunable with variations in static precompression, leading to controllable frequency shifts in a large band gap. A modal analysis reveals that four of the six principal wave modes are susceptible to external precompression while two modes are not

High reliability sheathed, beryllia insulated, tungsten-rhenium alloy thermocouple assemblies; their fabrication and EMF stability

Tantalum sheathed, BeO insulated, W-3% Re/W-25% Re thermocouple assemblies were fabricated and their emf drift determined during 2059 hours of exposure at 2073 K in a gaseous helium environment. The sheathed thermocouple assemblies were constructed from aged thermoelements, specially heat-treated BeO insulators, and specially cleaned and etched tantalum sheaths. Their thermal emf drifts ranged from the equivalent of only -0.3 to -0.8 K drift per 1000 hours of exposure at 2073 K. No evidence of any gross chemical attack or degradation of the component materials was found. The emf drift and material behavior of some unsheathed, BeO insulated, W-3% Re/W-25% Re thermocouples at 2250 and 2400 K were also determined. Unsheathed thermocouples tested in an argon environment at 2250 K for 1100 hours and at 2400 K for 307 hours exhibited changes in thermal emf that typically ranged from the equivalent of a few degrees K to as much as +11 K. Post-test examinations of these thermocouples revealed some undesirable material degradation and interaction which included erosion of the BeO insulators and contamination of the thermoelements by tantalum from the tantalum blackbody enclosure in which the thermocouples were contained

Jurisdictional Amount in the Federal District Courts

In 1925, Judge Dobie, then professor of law at the University of Virginia, advanced a formula for determining the value of the matter in controversy in all federal question and diverse citizenship cases in the federal district courts. He called it a plaintiff-viewpoint rule, and stated it thus: The amount in controversy in the United States District Court is always to be determined by the value to the plaintiff of the right which he in good faith asserts in his pleading that sets forth the operative facts which constitute his cause of action. Since then, the rule has received sanction and support from eminently respectable authority. Judge Clark of the Second Circuit has said, This, the so-called plaintiff\u27s viewpoint test ... seems now well settled. ..,\u27 and Judge Parker of the Fourth Circuit has said, It is well settled that the measure of jurisdiction in a suit for injunction is the value to plaintiff of the right which he seeks to protect. Similarly, Moore, in his Federal Practice, wrote, It must be said, however, that the prevailing note of the decisions and the impulses of logic and expediency indicate that the amount in controversy should be determined from the standpoint of the plaintiff, and Judge Yankwich, in an article published in the Federal Rules Decisions, wrote, As a general proposition, it may be said that the test for determining the existence of the jurisdictional minimum is the value to the plaintiff of the right which he seeks to assert. \u27 Numerous writers for law reviews have taken a similar attitude

Bio-inspired swing leg control for spring-mass robots running on ground with unexpected height disturbance

We proposed three swing leg control policies for spring-mass running robots, inspired by experimental data from our recent collaborative work on ground running birds. Previous investigations suggest that animals may prioritize injury avoidance and/or efficiency as their objective function during running rather than maintaining limit-cycle stability. Therefore, in this study we targeted structural capacity (maximum leg force to avoid damage) and efficiency as the main goals for our control policies, since these objective functions are crucial to reduce motor size and structure weight. Each proposed policy controls the leg angle as a function of time during flight phase such that its objective function during the subsequent stance phase is regulated. The three objective functions that are regulated in the control policies are (i) the leg peak force, (ii) the axial impulse, and (iii) the leg actuator work. It should be noted that each control policy regulates one single objective function. Surprisingly, all three swing leg control policies result in nearly identical subsequent stance phase dynamics. This implies that the implementation of any of the proposed control policies would satisfy both goals (damage avoidance and efficiency) at once. Furthermore, all three control policies require a surprisingly simple leg angle adjustment: leg retraction with constant angular acceleration

Guest Editorial Special Issue on: Big Data Analytics in Intelligent Systems

The amount of information that is being created, every day, is quickly growing. As such, it is now more common than ever to deal with extremely large datasets. As systems develop and become more intelligent and adaptive, analysing their behaviour is a challenge. The heterogeneity, volume and speed of data generation are increasing rapidly. This is further exacerbated by the use of wireless networks, sensors, smartphones and the Internet. Such systems are capable of generating a phenomenal amount of information and the need to analyse their behaviour, to detect security anomalies or predict future demands for example, is becoming harder. Furthermore, securing such systems is a challenge. As threats evolve, so should security measures develop and adopt increasingly intelligent security techniques. Adaptive systems must be employed and existing methods built upon to provide well-structured defence in depth. Despite the clear need to develop effective protection methods, the task is a difficult one, as there are significant weaknesses in the existing security currently in place. Consequently, this special issue of the Journal of Computer Sciences and Applications discusses big data analytics in intelligent systems. The specific topics of discussion include the Internet of Things, Web Services, Cloud Computing, Security and Interconnected Systems

The urban geography of Beirut

This thesis concentrates on those factors important to the geography of the economic and social organisation of Beirut for which reasonably reliable material could be obtained. This results in three main groups, namely the pattern of land values (III), the socio-economic morphology (IV) and business land use (V). Two minor sections, the physical background (I) and the historical background (II) introduce the physical and temporal setting of the city. The land values pattern exhibits features characteristic of both western and non western cities, with the direction of change being distinctly towards the western pattern. The same is true of the socio-economic morphology and the business land use. Relics of the old oriental pattern still stand out against the flood-tide of increasing westernisation. Further, there is marked a real differentiation of rate of change within the city itself. Wherever possible, material has been quantified to provide a basis for future comparative studies. Elsewhere comments are based on personal study of the situation with local inhabitants. The increasingly sophisticated nature of urban theory is recognised by the author but in view of the lack of comparative data this thesis remains a largely empirical study. It is hoped that it will add to the compendium of individual studies of Middle Eastern cities on which comprehensive theories of Middle Eastern urban geography can in future be based

Executive control systems in the engineering design environment

An executive control system (ECS) is a software structure for unifying various applications codes into a comprehensive system. It provides a library of applications, a uniform access method through a cental user interface, and a data management facility. A survey of twenty-four executive control systems designed to unify various CAD/CAE applications for use in diverse engineering design environments within government and industry was conducted. The goals of this research were to establish system requirements to survey state-of-the-art architectural design approaches, and to provide an overview of the historical evolution of these systems. Foundations for design are presented and include environmental settings, system requirements, major architectural components, and a system classification scheme based on knowledge of the supported engineering domain(s). An overview of the design approaches used in developing the major architectural components of an ECS is presented with examples taken from the surveyed systems. Attention is drawn to four major areas of ECS development: interdisciplinary usage; standardization; knowledge utilization; and computer science technology transfer

The dark side of I2P, a forensic analysis case study

© 2017 The Author(s). File sharing applications, which operate as a form of Peer-to-Peer (P2P) network, are popular amongst users and developers due to their heterogeneity, decentralized approach and rudimentary deployment features. However, they are also used for illegal online activities and often are infested with malicious content such as viruses and contraband material. This brings new challenges to forensic investigations in detecting, retrieving and examining the P2P applications. Within the domain of P2P applications, the Invisible Internet Project (IP2) is used to allow applications to communicate anonymously. As such, this work discusses its use by network node operators and known attacks against privacy or availability of I2P routers. Specifically, we investigate the characteristics of I2P networks in order to outline the security flaws and the issues in detecting artefacts within the I2P. Furthermore, we present a discussion on new methods to detect the presence of I2P using forensic tools and reconstruct specific I2P activities using artefacts left over by network software