High-strength tungsten alloy with improved ductility

Alloy combines superior strength at elevated temperatures with improved ductility at lower temperatures relative to unalloyed tungsten. Composed of tungsten, rhenium, hafnium, and carbon, the alloy is prepared by consumable electrode vacuum arc-melting and can be fabricated into rod, plate, and sheet

Failure to Conform to the Building Code; Its Effect on the Contracting Parties

The issue of the right of recovery by a building contractor who has failed to comply literally with specifications of building codes and ordinances has provoked much discussion and has brought forth opinions from courts and text writers, many of which are diametrically opposed. The authorities are generally agreed that a contract, whether it be a building contract or not, which upon execution will, by the thing which it tends to create, breach a positive law, is void and unenforceable. But, as is true of other rules of law which can not and do not have universal application, the courts will grant exceptions if justice will be better served by so doing. In considering the nature of the law which has been positively and expressly codified and its effect invalidating an agreement which, by its provisions, violates the law, the authorities have found that building ordinances as well as statutes should be given practical application and interpreted in the light of the conditions and circumstances under which they are passed and the objects sought to be attained

How Should Commercial Real Estate Be Priced?

When it comes to real estate pricing, most investors revert to the cap rate because it\u27s simple, and it\u27s the norm of the industry. But a correlation analysis indicates that cap rates have been largely unresponsive to alternative rates of return available to investors, with the exception of BBB bonds, over most of the past 25 years. Other pricing tools such as the Capital Asset Pricing Model; a comparative analysis with assets of similar credit risk; and the Gordon Dividend Growth Model provide much more elegant, yet still simple, alternatives to evaluating real estate pricing

The mechanical response of semiflexible networks to localized perturbations

Previous research on semiflexible polymers including cytoskeletal networks in cells has suggested the existence of distinct regimes of elastic response, in which the strain field is either uniform (affine) or non-uniform (non-affine) under external stress. Associated with these regimes, it has been further suggested that a new fundamental length scale emerges, which characterizes the scale for the crossover from non-affine to affine deformations. Here, we extend these studies by probing the response to localized forces and force dipoles. We show that the previously identified nonaffinity length [D.A. Head et al. PRE 68, 061907 (2003).] controls the mesoscopic response to point forces and the crossover to continuum elastic behavior at large distances.Comment: 16 pages, 18 figures; substantial changes to text and figures to clarify the crossover to continuum elasticity and the role of finite-size effect

Methodology for urban rail and construction technology research and development planning

A series of transit system visits, organized by the American Public Transit Association (APTA), was conducted in which the system operators identified the most pressing development needs. These varied by property and were reformulated into a series of potential projects. To assist in the evaluation, a data base useful for estimating the present capital and operating costs of various transit system elements was generated from published data. An evaluation model was developed which considered the rate of deployment of the research and development project, potential benefits, development time and cost. An outline of an evaluation methodology that considered benefits other than capital and operating cost savings was also presented. During the course of the study, five candidate projects were selected for detailed investigation; (1) air comfort systems; (2) solid state auxiliary power conditioners; (3) door systems; (4) escalators; and (5) fare collection systems. Application of the evaluation model to these five examples showed the usefulness of modeling deployment rates and indicated a need to increase the scope of the model to quantitatively consider reliability impacts

Shaping Supervised Agricultural Experiences in Rural American Schools: Support, Supervision, and Culture

Over the years, examination of barriers to the development and implementation of Supervised Agricultural Experience (SAE) programs has gained traction. This has led the profession to investigate the relevance of SAE. In the conducted studies, the profession continually notes that SAE remains a foundational component and perhaps the only distinguishing difference between school-based agriscience education (SBAE) and other Career and Technical Education programs or specialty courses that tie in a student leadership organization. While collecting evidence of perceived barriers of SAE implementation is important, at some point the question must be asked: What is right with student SAE programs in SBAE? This study used a qualitative approach to examine factors that exist in rural SBAE programs that maintain exemplary SAE programs. Through focus groups, one-on-one interviews, observations, and informal interviews, nine factors, embedded in three themes, emerged. Researchers concluded a culture for SAE existed throughout the total program, school, and community. It was recommended that agriculture teachers aspire to instill SAE culture within their program

Exploiting the Structure in DHT Overlays for DoS Protection

Peer to Peer (P2P) systems that utilize Distributed Hash Tables (DHTs) provide a scalable means to distribute the handling of lookups. However, this scalability comes at the expense of increased vulnerability to specific types of attacks. In this paper, we focus on insider denial of service (DoS) attacks on such systems. In these attacks, nodes that are part of the DHT system are compromised and used to flood other nodes in the DHT with excessive request traffic. We devise a distributed lightweight protocol that detects such attacks, implemented solely within nodes that participate in the DHT. Our approach exploits inherent structural invariants of DHTs to ferret out attacking nodes whose request patterns deviate from "normal" behavior. We evaluate our protocol's ability to detect attackers via simulation within a Chord network. The results show that our system can detect a simple attacker whose attack traffic deviates by as little as 5\% from a normal request traffic. We also demonstrate the resiliency of our protocol to coordinated attacks by up to as many as 25\% of nodes. Our work shows that DHTs can protect themselves from insider flooding attacks, eliminating an important roadblock to their deployment and use in untrusted environments

SOS: An Architecture for Mitigating DDoS Attacks

We propose an architecture called secure overlay services (SOS) that proactively prevents denial of service (DoS) attacks, including distributed (DDoS) attacks; it is geared toward supporting emergency services, or similar types of communication. The architecture uses a combination of secure overlay tunneling, routing via consistent hashing, and filtering. We reduce the probability of successful attacks by: 1) performing intensive filtering near protected network edges, pushing the attack point perimeter into the core of the network, where high-speed routers can handle the volume of attack traffic and 2) introducing randomness and anonymity into the forwarding architecture, making it difficult for an attacker to target nodes along the path to a specific SOS-protected destination. Using simple analytical models, we evaluate the likelihood that an attacker can successfully launch a DoS attack against an SOS-protected network. Our analysis demonstrates that such an architecture reduces the likelihood of a successful attack to minuscule levels. Our performance measurements using a prototype implementation indicate an increase in end-to-end latency by a factor of two for the general case, and an average heal time of less than 10 s