Search results for "Exchange"
showing 10 items of 2035 documents
Balancing Flexibility and Coherence: Information Exchange in a Paper Machinery Project
1999
The problem of balancing coherence and flexibility in collaborative information system design is approached here with two pairs of concepts. Boundary objects can support communication for perspective taking between communities of practice. Conscripting devices can support communication for perspective making within a community of practice. These theoretical lenses are used to study the uses of the technical specification in paper machine projects. Our study showed that as a boundary object it provided enough flexibility to allow negotiations, and sufficient local structure, for carrying out work in both communities of practice, the customer and the manufacturer. As a conscription device in …
Hydraulic vs. Electric: A Review of Actuation Systems in Offshore Drilling Equipment
2016
This article presents a survey on actuation systems encountered in offshore drilling applications. Specifically, it focuses on giving a comparison of hydraulic and electric drivetrains along with detailed explanations of their advantages and drawbacks. A significant number of industrial case studies is examined in addition to the collection of academic publications, in order to accurately describe the current market situation. Some key directions of research and development required to satisfy increasing demands on powertrains operating offshore are identified. The impact of the literature and application surveys is further strengthened by benchmarking two designs of a full-scale pipe handl…
Energy flexibility in Mediterranean buildings: a case-study in Sicily
2020
Since the building sector is responsible for 40% of the world’s electricity demand, it is essential to act on it in order to reduce emissions of climate change gases on a global scale, as expressed also in the latest directive on the energy performance of buildings. A design approach that focuses on the energy flexibility of buildings can contribute to the improvement of its energy-environmental performances. In this context, the objective of the study is the analysis of the energy performance of a residential building in Sicily and the definition of strategies aimed at increasing its energy flexibility. In particular, the case study is a 631 m2single-family house, modeled and simulated in …
Incentives in Corporate Governance: The Role of Self-Regulation
2004
Corporate governance stems from the interplay of legal norms, security regulation, self-regulation and best practices. Recent scandals and frauds have forced governments to update laws on corporate governance: the legislation process has been very fast in some countries, others have lagged. Law and regulation intervene and become effective only ex-post, when damages have been done and malpractice is self-evident. On the contrary, self-regulation is a quicker and more flexible response to changing market conditions and of great impact on the relationship between firms and their environment. A self-regulatory organization (SRO) such as the stock exchange could administer the screening device,…
Why Is Equity Order Flow so Persistent?
2014
Order flow in equity markets is remarkably persistent in the sense that order signs (to buy or sell) are positively autocorrelated out to time lags of tens of thousands of orders, corresponding to many days. Two possible explanations are herding, corresponding to positive correlation in the behavior of different investors, or order splitting, corresponding to positive autocorrelation in the behavior of single investors. We investigate this using order flow data from the London Stock Exchange for which we have membership identifiers. By formulating models for herding and order splitting, as well as models for brokerage choice, we are able to overcome the distortion introduced by brokerage. O…
Investigation of Flow and Heat Transfer in Corrugated-Undulated Plate Heat Exchangers
2000
An experimental and numerical investigation of heat transfer and fluid flow was conducted for corrugated-undulated plate heat exchanger configurations under transitional and weakly turbulent conditions. For a given geometry of the corrugated plates the geometrical characteristics of the undulated plates, the angle formed by the latter with the main flow direction, and the Reynolds number were made to vary. Distributions of the local heat transfer coefficient were obtained by using liquid-crystal thermography, and surface-averaged values were computed; friction coefficients were measured by wall pressure tappings. Overall heat transfer and pressure drop correlations were derived. Three-dimen…
Investigation of flow and heat transfer in corrugated passages—II. Numerical simulations
1996
An experimental and numerical study of flow and heat transfer was conducted for a crossed-corrugated geometry, representative of compact heat exchangers under transitional and weakly turbulent conditions. Three-dimensional numerical predictions were obtained by a finite volume method using a variety of approaches ranging from laminar flow assumptions to standard and low-Reynolds number k-e turbulence models, direct simulation, and large-eddy simulation. In this paper, the various computational approaches are presented and their relative performance is discussed for various geometries and Reynolds numbers; results are compared with experimental measurements and literature data. Detailed expe…
PERFORMANCE EVALUATION OF CASCADE REFRIGERATION SYSTEMS USING DIFFERENT REFRIGERANTS
2012
Due to the negative effects of synthetic refrigerants on the environment, natural refrigerants have obtained again interest as alternative refrigerants for different applications because of their zero ODP and negligible GWP. This paper presents a thermodynamic analysis of different two-stage cascade refrigeration systems using as refrigerant carbon dioxide (R744) in low-temperature circuit, and, respectively, ammonia (R717), propane (R290), butane (R600), R404A, R410A and R134a in high-temperature circuit. The operating parameters considered in this study include condensing and evaporating temperatures in high-temperature circuit, temperature difference in the cascade heat exchanger, and e…
Local Effects of Longitudinal Heat Conduction in Plate Heat Exchangers
2007
Abstract In a plate heat exchanger, heat transfer from the hot to the cold fluid is a multi-dimensional conjugate problem, in which longitudinal heat conduction (LHC) along the dividing walls often plays some role and can not be neglected. Large-scale , or end-to-end, LHC is always detrimental to the exchanger’s effectiveness. On the contrary, if significant non-uniformities exist in the distribution of either convective heat transfer coefficient, small-scale , or local, LHC may actually enhance the exchanger’s performance by improving the thermal coupling between high heat transfer spots located on the opposite sides of the dividing wall.
Heat exchangers and linear image processing theory
1989
Abstract This paper shows that the transient analysis of some heat exchangers can be derived easily with the linear equations of image processing theory. Partial differential equations of the cross-flow, parallelflow and rotary heat exchangers are considered together with the corresponding discrete models for linear image processing. Some numerical examples show that the nature of the heat and/or mass transfer problems is similar to those of image processing.