Implementation of Standard Solar PV Projects in Nigeria

The basic operating principle of Photovoltaic device is the conversion of solar irradiation into electricity. There are several applications of this principle. In Nigeria, most solar PV projects are designed for street lighting, water pumping and general stand-alone/minigrid rural electrifications. However, several solar PV projects being installed in various parts of this country fail to meet the minimum life-span due to a number of limiting factors. These include poor or improper fundamental design, use of sub-standard components, adoption of poor installation procedure by inexperienced personnel, bad construction/civil works among other factors. This has become a problem in the country and many are beginning to feel disgusted with solar PV projects as the heavy investments in such projects do not seem to be commensurate with their performances and satisfactions derivable. This paper therefore presents an overview of the performances of solar PV projects and a concise procedural approach to the implementation of standard solar PV projects in the country. In-depth analysis of performances of existing systems was also considered and the limiting factors identified with specific recommendations for improvement. We believe that if power projects are designed and executed properly by experienced technical experts, using the appropriate components and best technical procedures, standard PV projects with maximum performance output could be achieved

Gravitational stability and dynamical overheating of stellar disks of galaxies

We use the marginal stability condition for galactic disks and the stellar velocity dispersion data published by different authors to place upper limits on the disk local surface density at two radial scalelengths $R=2h$. Extrapolating these estimates, we constrain the total mass of the disks and compare these estimates to those based on the photometry and color of stellar populations. The comparison reveals that the stellar disks of most of spiral galaxies in our sample cannot be substantially overheated and are therefore unlikely to have experienced a significant merging event in their history. The same conclusion applies to some, but not all of the S0 galaxies we consider. However, a substantial part of the early type galaxies do show the stellar velocity dispersion well in excess of the gravitational stability threshold suggesting a major merger event in the past. We find dynamically overheated disks among both seemingly isolated galaxies and those forming pairs. The ratio of the marginal stability disk mass estimate to the total galaxy mass within four radial scalelengths remains within a range of 0.4---0.8. We see no evidence for a noticeable running of this ratio with either the morphological type or color index.Comment: 25 pages, 5 figures, accepted to Astronomy Letter

Mind the (treatment) gap: a global perspective on current and future strategies for prevention of fragility fractures

This narrative review considers the key challenges facing healthcare professionals and policymakers responsible for providing care to populations in relation to bone health. These challenges broadly fall into four distinct themes: (1) case finding and management of individuals at high risk of fracture, (2) public awareness of osteoporosis and fragility fractures, (3) reimbursement and health system policy and (4) epidemiology of fracture in the developing world. Findings from cohort studies, randomised controlled trials, systematic reviews and meta-analyses, in addition to current clinical guidelines, position papers and national and international audits, are summarised, with the intention of providing a prioritised approach to delivery of optimal bone health for all. Systematic approaches to case-finding individuals who are at high risk of sustaining fragility fractures are described. These include strategies and models of care intended to improve case finding for individuals who have sustained fragility fractures, those undergoing treatment with medicines which have an adverse effect on bone health and people who have diseases, whereby bone loss and, consequently, fragility fractures are a common comorbidity. Approaches to deliver primary fracture prevention in a clinically effective and cost-effective manner are also explored. Public awareness of osteoporosis is low worldwide. If older people are to be more pro-active in the management of their bone health, that needs to change. Effective disease awareness campaigns have been implemented in some countries but need to be undertaken in many more. A major need exists to improve awareness of the risk that osteoporosis poses to individuals who have initiated treatment, with the intention of improving adherence in the long term. A multisector effort is also required to support patients and their clinicians to have meaningful discussions concerning the risk-benefit ratio of osteoporosis treatment. With regard to prioritisation of fragility fracture prevention in national policy, there is much to be done. In the developing world, robust epidemiological estimates of fracture incidence are required to inform policy development. As the aging of the baby boomer generation is upon us, this review provides a comprehensive analysis of how bone health can be improved worldwide for all

Perbandingan Sifat Drawability Material Kaleng Kemasan Biscuit dan Cat Tembok

Salah satu jenis sampah atau limbah yang banyak ditemukan disekeliling kita adalah kaleng bekas kemasan dari berbagai produk kemasan. Banyak cara yang dapat dilakukan dalam pemanfaatan jenis sampah / limbah tersebut diantaranya adalah membentuk ulang untuk dijadikan suatu produk baru. Sifat drawability material merupakan salah satu hal yang penting dalam proses pembentukan logam lembaran. Dengan mengambil sampel kaleng bekas kemasan dari produk biscuit dan cat tembok, dalam studi ini ingin membandingkan sifat drawability atas kedua jenis material tersebut dengan cara melakukan beberapa jenis pengujian terhadap sampel. Data yang diperoleh menunjukan bahwa pada material kaleng bekas kemasan biscuit memiliki kadar karbon sebesar 0,03826% dan memiliki r-value <1 yaitu sebesar 0,6 serta nilai LDR 2 yaitu sebesar 2,3. Sedangkan pada material kaleng bekas kemasan cat tembok memiliki kadar karbon sebesar 0,0318% dengan nilai r-value 1 yaitu sebesar 1,8454 serta LDR 2 yaitu sebesar 3,296. Berdasarkan data-data tersebut dapat dikatakan bahwa material kaleng bekas kemasan cat tembok memiliki sifat drawability yang lebih baik bila dibandingkan dengan material kaleng bekas kemasan biscuit.Salah satu jenis sampah atau limbah yang banyak ditemukan disekeliling kita adalah kaleng bekas kemasan dari berbagai produk kemasan. Banyak cara yang dapat dilakukan dalam pemanfaatan jenis sampah / limbah tersebut diantaranya adalah membentuk ulang untuk dijadikan suatu produk baru. Sifat drawability material merupakan salah satu hal yang penting dalam proses pembentukan logam lembaran. Dengan mengambil sampel kaleng bekas kemasan dari produk biscuit dan cat tembok, dalam studi ini ingin membandingkan sifat drawability atas kedua jenis material tersebut dengan cara melakukan beberapa jenis pengujian terhadap sampel. Data yang diperoleh menunjukan bahwa pada material kaleng bekas kemasan biscuit memiliki kadar karbon sebesar 0,03826% dan memiliki r-value <1 yaitu sebesar 0,6 serta nilai LDR 2 yaitu sebesar 2,3. Sedangkan pada material kaleng bekas kemasan cat tembok memiliki kadar karbon sebesar 0,0318% dengan nilai r-value 1 yaitu sebesar 1,8454 serta LDR 2 yaitu sebesar 3,296. Berdasarkan data-data tersebut dapat dikatakan bahwa material kaleng bekas kemasan cat tembok memiliki sifat drawability yang lebih baik bila dibandingkan dengan material kaleng bekas kemasan biscuit