A simple method for determining Hf in Zr and Zr alloys by ICP-AES

This paper describes a rapid, accurate and precise method for determination of trace hafnium (Hf) in zirconium and zirconium alloys by inductively coupled plasma atomic emission spectrometry (ICP-AES). It was found that using a mixture of sulfuric acid (H_2SO_4) and ammonium sulfate (NH_4)_2SO_4, the total sample dissolution time was 15 min. Experimental works revealed that a high Zr concentration would result in a significant decrease in the peak height of the analyte lines, which was corrected by standard addition method. The performance of the developed method was evaluated by calculating the recovery percent and using standard reference material analysis.The recoveries were in the range of 97.6%-99.5% and the relative standard deviations were within 0.8%-3.0%. The detection limit (3σ) of Hf was found to be 0.01 μg·g~(-1), respectively. The proposed technique, with high precision and accuracy, was applied to the analysis of trace Hf in zirconium-niobium ingots and tubes for the first time in Iran.     

Process Model for Administrating Construction Claims

Claims for additional costs and time extensions result from a variety of events occurring during the course of construction. To enhance the chances of success, contractors submitting claims must closely follow the steps stipulated in the contract conditions, provide a breakdown of alleged additional costs and time, and present sufficient documentation. On the other hand, project owners need to follow an overall comprehensive step-by-step procedure for tracking and managing the claims submitted by contractors. The paper presents a claims-management process that could be used by all parties involved in construction. The process identifies the major information-gathering and decision-making milestones as well as the notice and substantiation compliance checkpoints, which are critical to the development of defense arguments as claims are addressed. It further emphasizes the use of tools such as simulation, scheduling, productivity, and economic analysis and other modeling techniques in judging the level of justification and reasonableness of submitted claims.     

Reducing current and future risks: Using climate change scenarios to test an agricultural conservation framework

Evaluating the potential effects of changes in climate on conservation practices can help inform strategies to protect freshwater biodiversity that are robust, even as conditions change. Here we apply a climate change “test” to a framework for estimating the amount of agricultural conservation practices needed to achieve desired fish conservation outcomes for four watersheds in the Saginaw Bay region of Michigan, USA. We developed three climate scenarios from global climate model outputs (high emissions scenario, “2080s” timeframe) to provide insight on potential impacts of a climate driver that represents a key uncertainty for this management system, the amount and timing of spring and summer precipitation. These scenarios were used as inputs to agricultural watershed models, which produced water quality outputs that we compared to thresholds in fish biodiversity metrics at the subwatershed scale. Our results suggest that impacts of climate change on evaporation rates and other aspects of hydrology will shift the relative importance of key stressors for fish (i.e., sediment loadings vs. nutrient concentrations) across these different watersheds, highlighting the need to design resilient implementation plans and policies. Overall, we found that changes in climate are likely to increase the need for agricultural conservation practices, but that increasing the implementation rate above current levels will likely remain a good investment under current and future climate conditions.     

Optimizing Multiple-Pollutant Waste Load Allocation in Rivers: An Interval Parameter Game Theoretic Model

In this paper, a new methodology is developed for optimal multiple-pollutant waste load allocation (MPWLA) in rivers considering the main existing uncertainties. An interval optimization method is used to solve the MPWLA problem. Different possible scenarios for treatment of pollution loads are defined and corresponding treatment costs are taken into account in an interval parameter optimization model. A QUAL2Kw-based water quality simulation model is developed and calibrated to estimate the concentration of the water quality variables along the river. Two non-cooperative and cooperative multiple-pollutant scenario-based models are proposed for determining waste load allocation policies in rivers. Finally, a new fuzzy interval solution concept for cooperative games, namely, Fuzzy Boundary Interval Variable Least Core (FIVLC), is developed for reallocating the total fuzzy benefit obtained from discharge permit trading among waste load dischargers. The results of applying the proposed methodology to the Zarjub River in Iran illustrate its effectiveness and applicability in multiple-pollutant waste load allocation in rivers.     

Finite element model updating of a large structure using multi-setup stochastic subspace identification method and bees optimization algorithm

In the present contribution, operational modal analysis in conjunction with bees optimization algorithm are utilized to update the finite element model of a solar power plant structure. The physical parameters which required to be updated are uncertain parameters including geometry, material properties and boundary conditions of the aforementioned structure. To determine these uncertain parameters, local and global sensitivity analyses are performed to increase the solution accuracy. An objective function is determined using the sum of the squared errors between the natural frequencies calculated by finite element method and operational modal analysis, which is optimized using bees optimization algorithm. The natural frequencies of the solar power plant structure are estimated by multi-setup stochastic subspace identification method which is considered as a strong and efficient method in operational modal analysis. The proposed algorithm is efficiently implemented on the solar power plant structure located in Shahid Chamran university of Ahvaz, Iran, to update parameters of its finite element model. Moreover, computed natural frequencies by numerical method are compared with those of the operational modal analysis. The results indicate that, bees optimization algorithm leads accurate results with fast convergence.     

Directional characteristics of cylindrical radiators with an arc-shaped acoustic screen

Directional sound radiation by a cylinder surrounded with an arc-shaped (open circular) acoustic screen is examined. The corresponding boundary problem is solved with the partial domain technique. The method of asymptotic solutions was used to verify the conditions of solving this problem using the method of simple reduction. As a result of the analysis, the quantitative characteristics of the acoustic field of the cylindrical radiator inside the arc-shaped screen were evaluated.     

Knowledge Management in Mechanical and Industrial Engineering Consulting: A Case Study

The goal of knowledge management as a process is to improve the organization’s ability to execute its core business functions more efficiently and effectively. The key to knowledge management is capturing intellectual assets for the tangible benefit of the organization. On the other hand, the aim of any design engineering consulting firm is to produce projects with high quality and in less time. The paper starts by discussing the importance of knowledge management in improving the competitive edge of firms in general and of consulting firms in particular. Then, the paper discusses the process of building a knowledge management system in the Mechanical and Industrial Department at DAR AL HANDASAH, which is a leading consulting firm in the Middle East and the world. The paper concludes with the lessons learned from the experience of building the knowledge management system and the steps needed to improve it.     

Morley’s theorem revisited: Origami construction and automated proof

Morley’s theorem states that for any triangle, the intersections of its adjacent angle trisectors form an equilateral triangle. The construction of Morley’s triangle by the straightedge and compass method is impossible because of the well-known impossibility result for angle trisection. However, by origami, the construction of an angle trisector is possible, and hence that of Morley’s triangle. In this paper we present a computational origami construction of Morley’s triangle and an automated correctness proof of the generalized Morley’s theorem.During the computational origami construction, geometrical constraints in symbolic representation are generated and accumulated. Those constraints are then transformed into algebraic forms, i.e. a set of polynomials, which in turn are used to prove the correctness of the construction. The automated proof is based on the Gröbner bases method. The timings of the experiments of the Gröbner bases computations for our proofs are given. They vary greatly depending on the origami construction methods, the algorithms for the Gröbner bases computation, and variable orderings.