In this article we are interested in the optimal choice of the tilt angle of solar water heaters, in the case of Tunis (lat 36°.85, long 10°.2). We studied several variations of usage months: spread all year round or solely reduced for some months: nine, seven or five months centered on winter - the most difficult period to satisfy in term of solar energy. Results show that a more elevated tilt of the collector for some degrees in relation to the latitude of the place [1] is essential especially if we want to make favorable the conditions of collecting in winter where resources in solar energy are at their minimum, whereas, the needs in hot water are at their maximum. In a second part of this article, means of conversion are given, for a collector plane tilt of an angle “i”, of the solar data of the received global and diffuse solar radiation by the horizontal plane. The results are resemble those of to Duffie [2] but the correlation is shorter. Thus, we can help laboratories which are not equipped with measure devices of solar energy; an apparent data to determine performances of all solar energy conversion system or using it as primary energy source. We can rely on solar data which will be converted according to both the tilt angle and the orientation of the solar panels.
"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."
"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."
"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."
"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."
"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."
"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."
"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."
"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."
"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."
"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."
"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."
"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."
"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."
"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."
"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."
"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."
"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."
"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."
"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."
"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."