Low-cost hot-air solar collector

System has only three components per cell. Cell parts are fabricated from readily available materials and, following a construction procedure which requires use of only simple handtools, can be mounted in place by one person

Self-regenerating desiccant system

Compact system uses inherent diurnal cyclic airflow in system and energy of sun as drying heat. System requires no power for operation, has no moving parts to wear out, requires no blowers or manifolds, and is relatively inexpensive to produce

Real-time representations of the output gap

Methods are described for the appropriate use of data obtained and analysed in real time to represent the output gap. The methods employ cointegrating VAR techniques to model real-time measures and realizations of output series jointly. The model is used to mitigate the impact of data revisions; to generate appropriate forecasts that can deliver economically meaningful output trends and that can take into account the end-of-sample problems encountered in measuring these trends; and to calculate probability forecasts that convey in a clear way the uncertainties associated with the gap measures. The methods are applied to data for the United States 1965q4–2004q4, and the improvements over standard methods are illustrated

The MVA Priority Approximation

A Mean Value Analysis (MVA) approximation is presented for computing the average performance measures of closed-, open-, and mixed-type multiclass queuing networks containing Preemptive Resume (PR) and nonpreemptive Head-Of-Line (HOL) priority service centers. The approximation has essentially the same storage and computational requirements as MVA, thus allowing computationally efficient solutions of large priority queuing networks. The accuracy of the MVA approximation is systematically investigated and presented. It is shown that the approximation can compute the average performance measures of priority networks to within an accuracy of 5 percent for a large range of network parameter values. Accuracy of the method is shown to be superior to that of Sevcik's shadow approximation

On the Role of Higher Twist in Polarized Deep Inelastic Scattering

The higher twist corrections $h^N(x)/Q^2$ to the spin dependent proton and neutron structure functions $g_1^N(x, Q^2)$ are extracted in a model independent way from experimental data on $g_1^N$ and found to be non-negligible. It is shown that the NLO QCD polarized parton densities determined from the data on g1, including higher twist effects, are in good agreement with those found earlier from our analysis of the data on g1/F1 and A1 where higher twist effects are negligible. On the contrary, the LO QCD polarized parton densities obtained from the data on g1, including higher twist, differ significantly from our previous results.Comment: 18 pages, latex, 6 figures, final version which will be published in Phys. Rev. D, fig. 5 is changed, misprints in Table 2 are remove

Phenomenological analysis of the lived experiences of academics who participated in the professional development programme at an Open Distance Learning (ODL) University in South Africa

Since online delivery of education has become a major approach to teaching in Open Distance Learning (ODL) institutions, it becomes critical to understand how academics learn to teach online. This study was designed to explore the lived experiences of academics who had participated in a professional development programme aimed at moving them from traditional distance teaching to online facilitation of learning. Giorgi’s phenomenological psychological method was used to analyse and retrospectively examine the learning experiences of the participant academics in order to establish how they lived, behaved and experienced the training programme. The participants described their experiences in relation to distinct lived worlds that included the world in relation to self, others, time, and their environment. The academics’ experiences and concerns provide insight into their skills development needs and the adequacy of the programme provided in addressing these and equipping academics for online teaching. The perspectives identified could serve to guide the development and promotion of professional development programmes for online teaching and learning