A general method for dynamic analysis of structures overview

The presented research deals with the development of a dynamic analysis method for structural systems. The modeling approach is essentially a finite element method in the sense that the structure is divided into n elements. An element is defined as any structural unit whose degree of freedom (dofs) can be categorized as either interface or non-interface dofs. An element could be a fundamental unit such as a rod, a beam, a plate etc., or it could be an entire structural component. Furthermore, the parameters for the element could be distributed or lumped. The choice of elements is totally arbitrary and is a matter of user convenience. In particular, issues of accuracy and convergence do not enter on the level of example that bookkeeping is reduced to a minimum. Each element is modeled using a set of interface constraint modes (ICM) combined with a set of interface restrained normal models (IRNM). The next step is the solution of the system eigenvalue problem. The procedure calls for the sequential solution of a number of small eigenvalue problems based on a truncation principle for IRNM. In addition, the form of these eigenvalue problems is very simple such that an escalator type of eigenvalue problem solver can be used which is extremely cost-effective and fast

Recipe theorems for polynomial invariants on ribbon graphs with half-edges

We provide recipe theorems for the Bollob\`as and Riordan polynomial $\mathcal{R}$ defined on classes of ribbon graphs with half-edges introduced in arXiv:1310.3708[math.GT]. We also define a generalized transition polynomial $Q$ on this new category of ribbon graphs and establish a relationship between $Q$ and $\mathcal{R}$.Comment: 24 pages, 14 figure

Teachers’ Experience and Teachers’ Competency Needs in the multidisciplinary approach to implementation of environmental education curriculum in Cross River State, Nigeria

The study was undertaken to determine teachers experience and their competence needs of teachers in the multidisciplinary approach to implementation of environmental education curriculum in Cross River State, Nigeria. One research question and one hypothesis were formulated to guide the study. The study adopted the descriptive survey design. The sample consisted of 737 teachers proportionally sampled from 67 public secondary schools in the three education zones of Cross River State. The teacher competence needs questionnaire in the implementation of environmental education curriculum containing competency needs items was used for data collection. The data were analyzed using means, standard deviation and t-test. Teachers’ experience (F=5.292; p<.05) significantly influenced their competence needs. Based on the findings, it was recommended among others under the multidisciplinary approach experience teachers should be well trained and retrain to be able implement EE curriculum

Electricity sector reality, economic security and national development in Nigeria: an elite theory dimension

The electricity sector is an immensely critical component of the equations in a 21st century economy. Economic security on the other hand is the essence of national development. The crucial question in this study therefore borders on the extent to which the electricity sector in Nigeria positively relates to economic security and how these variables ultimately link with national developmental dreams in this nation-state. We have made use of secondary sources of data and the elite theoretical framework in the conduct of the study. The methodology of the study is the critical mode of research. Our findings indicate that there are immense weak-linkages between Nigeria's electricity sector reality, economic security and national developmental aspirations in the country. And this is principally (un) driven by elite insensitivity. The paper emphasizes that a critical leadership challenge in Nigeria hinges on the appreciation of the import of these linkages by current and subsequent generations of national development planners in the Nigerian state

A mechatronic design synthesis for very low flow control valves

The means by which the control of very low flows in the region of 0.1-400ml/hr using valves with microchannels (<250μm) is not well defined. This work presents a review of existing literature that contributes to the understanding of controlling very low flows. Mechatronic principles are used to bring new understanding to the field of very low flow control using needle valves. Flow rate experiments were conducted using a mechatronically controlled needle valve and a novel flow measurement device constructed for the purpose, from which an analytical flow model is developed. Details of a linear actuated needle valve are given along with open loop and closed loop control systems developed for the purpose of accurately controlling very low flows. The open loop system is derived from the valve operating principles enabling an efficient method of modelling the valve flow characteristics for the purpose of control. The closed loop method, incorporating gain scheduling is capable of controlling flows to within 0.0016ml/hr at low flows. A prototype lubricant dispensing system using a low flow needle valve was tested in an industrial environment. A design synthesis is developed by consolidating the knowledge gained from these studies is presented. This discusses the all main factors affecting the design and operation of needle valves for the control of very low flows while describing practical solutions to the problems commonly encountered

Emerging viral respiratory tract infections—environmental risk factors and transmission

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.The past decade has seen the emergence of several novel viruses that cause respiratory tract infections in human beings, including Middle East respiratory syndrome coronavirus (MERS-CoV) in Saudi Arabia, an H7N9 influenza A virus in eastern China, a swine-like influenza H3N2 variant virus in the USA, and a human adenovirus 14p1 also in the USA. MERS-CoV and H7N9 viruses are still a major worldwide public health concern. The pathogenesis and mode of transmission of MERS-CoV and H7N9 influenza A virus are poorly understood, making it more difficult to implement intervention and preventive measures. A united and coordinated global response is needed to tackle emerging viruses that can cause fatal respiratory tract infections and to fill major gaps in the understanding of the epidemiology and transmission dynamics of these viruses