Ling Wang, Fujun Wang, Bryan William Karney, Ahmad Malekpour and Zhengwei Wang
The velocity head is usually neglected in the energy equation for a pipeline junction when one-dimensional (1D) hydraulic transient flow is solved by method of characteristics…
Abstract
Purpose
The velocity head is usually neglected in the energy equation for a pipeline junction when one-dimensional (1D) hydraulic transient flow is solved by method of characteristics. The purpose of this paper is to investigate the effect of velocity head on filling transients in a branched pipeline by an energy equation considering velocity head.
Design/methodology/approach
An interface tracking method is used to locate the air–water interface during pipeline filling. The pressured pipe flow is solved by a method of characteristics. A discrete gas cavity model is included to permit the occurrence of column separation. A universal energy equation is built by considering the velocity head. The numerical method is provisionally verified in a series pipeline and the numerical results and experimental data accord well with each other.
Findings
The numerical results show that some differences in filling velocity and piezometric head occur in the branched pipeline. These differences arise because the velocity head in the energy equation can become an important contributor to the hydraulic response of the system. It is also confirmed that a local high point in the profile is apt to experience column separation during rapid filling. Significantly, the magnitude of overpressure and cavity volume induced by filling transients at the local high point is predicted to increase with the velocity in the pipes.
Originality/value
The velocity head in the energy equation for a pipeline junction could play an important role in the prediction of filling velocity, piezometric head and column separation phenomenon, which should be given more attention in 1D hydraulic transient analysis.
Details
Keywords
Long Meng, Min He, Lingjiu Zhou, Jing Yang, Zhengwei Wang and Bryan Karney
– The purpose of this paper is to analyze the cavitation dynamics in the blade channel of a centrifugal pump with a particular focus on the direct influence of the pump’s volute.
Abstract
Purpose
The purpose of this paper is to analyze the cavitation dynamics in the blade channel of a centrifugal pump with a particular focus on the direct influence of the pump’s volute.
Design/methodology/approach
A homogeneous multiphase model, namely the Zwart-Gerber-Belamri cavitation model, is employed to numerically describe the evolution of the process of cavitation within the pump. The RNG k-e turbulence model is applied to analyze the unsteady turbulent flow. A second order implicit formulation is used for the time discretization for the unsteady flow calculation and a finite volume algorithm is used for the space discretization.
Findings
The cavities in the passage exhibit an obvious life cycle which includes initiation, growth, contraction, and separation, and collapse with a frequency corresponding to the impeller rotation frequency under off-design conditions. This phenomenon arises through an alternating interaction between reverse flow with the cavity interface and is associated with the response of the vortex region to the effect of uneven pressure distribution on volute and impeller-tongue interaction.
Originality/value
This study simulated and analyzed the complex transient cavitation flow patterns inside a centrifugal pump and explains the reason for the unsteadiness. This knowledge is instructive in achieving the stable operation of pumps and in trouble shooting rough or cavitating operation.
Details
Keywords
Purpose: This study examines the relationship between marital satisfaction and sexual satisfaction, as well as other contributing factors, in the lives of older American adults…
Abstract
Purpose: This study examines the relationship between marital satisfaction and sexual satisfaction, as well as other contributing factors, in the lives of older American adults.
Design/methodology/approach: Data from a restricted sample (N = 1,278) from the second wave of the National Social Life, Health, and Aging Project (NSHAP) was analyzed. Regression models were used to examine associations with marital satisfaction.
Findings: Within ordinary least squares regression gender, education level, mental health, self-rated happiness, the absence of sexual quality, physical satisfaction, and emotional satisfaction were each statistically significant. Females reported higher marital satisfaction than males. Higher educated individuals expressed less satisfaction within their marriages than those with less formal education. Those that rated their mental health, happiness, and physical and emotional satisfaction high also reported higher marital satisfaction. Participants that reported an absence of sexual quality generally rated their marital satisfaction lower.
Originality/value: Most studies focus on the experiences of younger and middle-aged adults, often excluding older adults. Further, while there have been efforts to focus more research on the relationships of adults in midlife to late life, sexuality is still largely ignored.
Details
Keywords
Because of the special “State of the States” issue of Library Hi Tech and other circumstances beyond my control, the four quarterly “Comp Lit” compilations for 1996 appear here in…
Abstract
Because of the special “State of the States” issue of Library Hi Tech and other circumstances beyond my control, the four quarterly “Comp Lit” compilations for 1996 appear here in a single and possibly peculiar chunk. A lot changes in a year of personal computing, but on reflection it seemed useful to include the citations and comments as I originally wrote them.
Carlo Gabriel Porto Bellini, Rita de Cássia de Faria Pereira and João Luiz Becker
The purpose of this paper is to discuss the structural design of customer teams (CuTes) working with external teams to implement customized information systems (IS). Design…
Abstract
Purpose
The purpose of this paper is to discuss the structural design of customer teams (CuTes) working with external teams to implement customized information systems (IS). Design consists of theoretically based measures and a first set of real-world, empirical values.
Design/methodology/approach
A search in the organizational literature suggested that the adhocracy is the preferred structure for CuTes. Adhocracy-like measures were then developed and applied to a high-performance CuTe to reveal a first benchmark for a team’s adhocratic design.
Findings
High-performance CuTes do not necessarily implement the adhocratic principles to the highest degree.
Research limitations/implications
It is still open whether all the structural measures described here are necessary and sufficient to describe the adhocracy-like structural design of CuTes.
Practical implications
The CuTe is highlighted as the key incumbent of cooperation with the technology supplier and consultants in terms of project authority and responsibility. A psychometric instrument and real-world values are proposed as a reference for the structural design of high-performance CuTes.
Social implications
The performance of IS projects is a social concern, since IS products should be aimed at serving people better both inside and outside the organization. Professionals who work in CuTes to develop better IS should receive institutional recognition and management attention.
Originality/value
This study seems to be the first to discuss the structure of CuTes in customized IS projects from a theoretical and applied perspective.