Prediction of Corner Mechanical Properties for Stainless Steels Due to Cold Forming

The results of a study of the degree of workhardening on stainless steel Types 304, 409, 430 and Type 3CR12 corrosion resisting steel due to cold work of forming are presented in this paper. Analytical inelastic stress-strain relationships are established for virgin tensile specimens. An equation for predicting the yield strength of comers are developed

The Lateral Torsional Buckling Strength of Cold-formed Stainless Steel Lipped Channel Beams

The findings of an investigation into the lateral buckling strength of cold-formed singly-symmetric stainless steel beams are reported in this study. The singly-symmetric sections under consideration were lipped channel sections fabricated from a modified AISI stainless steel Type 409 designated 3CR12, a ferritic corrosion resisting steel. The purpose of this study was to compare the experimental strengths of singly-symmetric sections to the theoretical predictions proposed by the new ASCE Specification for the Design of Cold-Formed Stainless Steel Structural Members. It was concluded in this investigation that the tangent modulus approach adopted in the design specification for stainless steels, compared well with the experimental results

Burst Strength of Type 304L Stainless Steel Tubes Subjected to Internal Pressure and External Forces

The findings of an investigation concerning the burst strength of cold-formed Type 304L stainless steel tubes subjected to internal pressure and static external forces are reported in this study. The use of cold-formed stainless steel longitudinally welded tube in pressurised processes in industry are limited due to the belief that seamless tubes have superior resistance to internal pressure. The primary objective of this study was to experimentally and theoretically describe the failure criteria for thin-walled longitudinally welded Type 304L stainless steel tubes subjected to internal pressure and static external point loads and torsion loads. Due to the diversity of the pipe manufacturing process, problem areas which were most likely to cause failures were identified. A microscopic study was done of the weld region where failure was expected in order to support the test results. It was found that cold-formed longitudinally welded Type 304L stainless steel tubes could attain very high bursting pressure values and could compete with seamless tubes in this respect. It was also found that the internal pressure was the most important criteria in tube failure and that the effect of static external forces could be neglected to a certain extent

Potts models in the continuum. Uniqueness and exponential decay in the restricted ensembles

In this paper we study a continuum version of the Potts model. Particles are points in R^d, with a spin which may take S possible values, S being at least 3. Particles with different spins repel each other via a Kac pair potential. In mean field, for any inverse temperature there is a value of the chemical potential at which S+1 distinct phases coexist. For each mean field pure phase, we introduce a restricted ensemble which is defined so that the empirical particles densities are close to the mean field values. Then, in the spirit of the Dobrushin Shlosman theory, we get uniqueness and exponential decay of correlations when the range of the interaction is large enough. In a second paper, we will use such a result to implement the Pirogov-Sinai scheme proving coexistence of S+1 extremal DLR measures.Comment: 72 pages, 1 figur

Benchmarking online dispatch algorithms for Emergency Medical Services

Providers of Emergency Medical Services (EMS) face the online ambulance dispatch problem, in which they decide which ambulance to send to an incoming incident. Their objective is to minimize the fraction of arrivals later than a target time. Today, the gap between existing solutions and the optimum is unknown, and we provide a bound for this gap.Motivated by this, we propose a benchmark model (referred to as the offline model) to calculate the optimal dispatch decisions assuming that all incidents are known in advance. For this model, we introduce and implement three different methods to compute the optimal offline dispatch policy for problems with a finite number of incidents. The performance of the offline optimal solution serves as a bound for the performance of an - unknown - optimal online dispatching policy.We show that the competitive ratio (i.e., the worst case performance ratio between the optimal online and the optimal offline solution) of the dispatch problem is infinitely large; that is, even an optimal online dispatch algorithm can perform arbitrarily bad compared to the offline solution. Then, we performed benchmark experiments for a large ambulance provider in the Netherlands. The results show that for this realistic EMS system, when dispatching the closest idle vehicle to every incident, one obtains a fraction of late arrivals that is approximately 2.7 times that of the optimal offline policy. We also analyze another online dispatch heuristic, that manages to reduce this gap to approximately 1.9. This constitutes the first quantification of the gap between online and offline dispatch policies