Structural Optimization and Strength Analysis of the Lifting Arm of a Wet Shotcrete Spraying Unit北大核心CSCD

Wet shotcrete spraying units are widely used in underground engineering, for railways, highways, water conservancy and hydropower stations, municipal works, mining and military and other industries. Structural analysis and mechanical behavior optimization are conducted regarding the lifting arm of a TKJ series shotcrete spraying unit, and optimization of the hinge point position and working scope of the lifting arm is realized. The optimal layout scheme for the hinge force is given based on the Monte Carlo method, the hinge force of the lifting arm is improved for the mean and maximum values, and the maximum and average hinge force of the lifting cylinder decrease by 23.14% and 7.70%, respectively, compared with that of the original scheme. The static strength is checked using Ansys-Workbench for the optimized scheme, and the results show that the optimized scheme has a larger safety re-serve and that the structural design is more reasonable than the original scheme. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 1

This paper is review of the characterization of exhaust particles from state-of-the-art internal combustion engines. We primarily focus on identifying the physical and chemical properties of nano-particles, i.e., the concentration, size distribution, and particulate matter (PM) morphology. Stringent emissions regulations of the Euro 6 and the LEV III require a substantial reduction in the PM emissions from vehicles, and improvements in human health effects. Advances in powertrains with sophisticated engine control strategies and engine after-treatment technologies have significantly improved PM emission levels, motivating the development of new particle measurement instruments and chemical analysis procedures. In this paper, recent research trends are reviewed for physical and chemical PM characterization methods for gasoline and diesel fueled engines under various vehicle certification cycles and real-world driving conditions. The effects of engine technologies, fuels, and engine lubricant oils on exhaust PM morphology and compositions are also discussed.     

Inventory,Classification, and Analysis of Special Management Areas Associated with U.S. Coastal Programs

Area-based management approaches may be beneficial in integrating sectoral, single-purpose laws and regulations; however, these benefits may not be attained if special area designations are equally sectoral or single-purpose in nature. Over 60 types of special management areas were documented under U.S. coastal programs, and a new classification scheme was developed to allow comparisons and analyses across programs. Results indicate that requirements and incentives for special area designations under the Coastal Zone Management Act did little to standardize or influence area-based management systems associated with state and territory coastal programs. Further, the absence of clear patterns within and between coastal programs with respect to special area policies suggests a limited commitment to this important aspect of coastal management. Continued research is needed to document the effectiveness of the various area-based management approaches presented in this article.     

Model-based analysis of the mechanical subsystem of an air brake system

Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem of the air brake system were performed, and the results are corroborated with experimental data.     

A user‐resource planning framework for offshore recreational artificial reefs

Abstract

Artificial reefs have been used extensively in coastal waters to attract and enhance recreational fishery resources. In the United States, they have been traditionally built from “materials of opportunity”; using limited budgets. This paper explores some past planning philosophies and presents a recent artificial reef deployment case that demonstrates a lack of sensitivity to local and regional recreational demand. A systems framework is developed to guide future planning efforts in artificial reef development. The framework is intended to integrate previously fragmented knowledge and to demonstrate the interdisciplinary nature of artificial reef planning. Emphasis is given to advance planning, user dimensions, and the integral issue of reef access.     

The Impact of Recreation on Barrier Islands: A Case Study on Masonboro Island

Since 1992, coastal researchers at the University of North Carolina at Wilmington have been documenting the impacts of human recreational use on Masonboro Island, a component of the North Carolina National Estuarine Research Reserve, and the subsequent natural processes that mitigate these impacts. Both short-term and long-term natural mitigational processes were identified. The effects of these processes were found to be much more rapid than similar impacts on typical terrestrial settings. However, careful examination of the data suggests that both physical location of the impact site and natural variability of weather patterns and events play a role. Management implications of these findings are proposed.     

Coastal communities—partners or puppets in outer continental shelf development

This article reviews the history of esthetics and its role in the development of outdoor recreation policy. Current research is also reviewed, demonstrating the broad scope and complexity of esthetics as a focus for research. Finally, in the absence of sufficient research for formulating coastal recreation planning and management decisions, the ethics of coastal recreation “development”; is considered.     

Evaluating the energy performance of a SUV hybrid electric vehicle

This paper analyzes the energetic performance of the hybrid Lexus RX 400h, through on-board measurements. Several speed profiles were analyzed, for three driving types, successive stop and go cycles, three speed profiles, crossing an electronic toll collection booth, and a roundabout. In stop and go situations the internal combustion engine did not work (the torque needed to impulse the vehicle in the stop and go situations was only supported by the electric engines), as well as in the situations of constant low speeds (50 or 60 km h^?1). The auxiliary support given by the electric engines in the accelerations, as well as the importance of the energy regeneration system on the batteries’ load recovery is also demonstrated. When compared with similar conventional vehicles, the Lexus RX 400h has lower combined energy consumption between 1.2% and 60%.     

A regional railroad network optimization model for coal transportation

A regional railroad network is presented to evaluate the system's response to increased coal traffic. An optimal, multimodal, coal-shipping pattern is developed for the study region to minimize total costs and to efficiently use the existing network. A two-stage, general model allocates resources among demands and then assigns flows to the network according to efficiency criteria. The model is sufficiently general to permit modification for specific needs, assumptions and data. Government agencies and industries can apply the model in resource allocation decisions and transportation policy analysis.     

A risk model for the operation of container vessels

Commercial shipping of containerized goods involves certain risks for human safety and environment. In order to actively manage these risks, they must be identified, analyzed, modeled, and quantified. This requires a systematical analysis of design and operation of container vessels. Within the EU-funded research project SAFEDOR, a Formal Safety Assessment has been applied to establish the current safety level of generic container ships and to identify potential cost-effective risk control options. This paper describes a structured approach to develop the underlying high-level risk model. It is structured as risk contribution tree consisting of a series of fault trees and event trees for the major accident categories. Statistical analysis of casualty data is used to estimate the probability of occurrence. Finally, the summation overall individual risk contributions yields the current risk pro file for the operation of container vessels is presented as FN-curve.