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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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HVAC
Heating, ventilation, and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation, as HVAC&R or HVACR or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels and senior living facilities, medium to large industrial and office buildings such as skyscrapers and hospitals, on ships and submarines, and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors. Ventilating or ventilation (the V in HVAC) is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical/forced and natural types.
  • 2.7K
  • 10 Nov 2022
Topic Review
Dysgraphia
Dysgraphia is a learning disability of written expression, that affects the ability to write, primarily handwriting, but also coherence. It is a specific learning disability (SLD) as well as a transcription disability, meaning that it is a writing disorder associated with impaired handwriting, orthographic coding and finger sequencing (the movement of muscles required to write). It often overlaps with other learning disabilities and neurodevelopmental disorders such as speech impairment, attention deficit hyperactivity disorder (ADHD) or developmental coordination disorder (DCD). In the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), dysgraphia is characterized as a learning disability in the category of written expression, when one's writing skills are below those expected given a person's age measured through intelligence and age-appropriate education. The DSM is unclear in whether writing refers only to the motor skills involved in writing, or if it also includes orthographic skills and spelling. Dysgraphia should be distinguished from agraphia (sometimes called acquired dysgraphia), which is an acquired loss of the ability to write resulting from brain injury, progressive illness, or a stroke. The prevalence of dysgraphia throughout the world is not known, due to difficulties in diagnosis and lack of research.
  • 5.4K
  • 10 Nov 2022
Topic Review
Transwiki: Multiregional Origin of Modern Humans
The multiregional hypothesis is a scientific model that provides an explanation for the pattern of human evolution. The hypothesis holds that humans first arose near the beginning of the Pleistocene two million years ago and subsequent human evolution has been within a single, continuous human species. This species encompasses archaic human forms such as Homo erectus and Neanderthals as well as modern forms, and evolved worldwide to the diverse populations of modern Homo sapiens sapiens. The theory contends that humans evolve through a combination of adaptation within various regions of the world and gene flow between those regions. Proponents of multiregional origin point to fossil and genomic data and continuity of archaeological cultures as support for their hypothesis. The primary alternative hypothesis is recent African origin of modern humans, which contends that modern humans arose in Africa around 100-200,000 years ago, moving out of Africa around 50-60,000 years ago to replace archaic human forms without interbreeding.
  • 8.8K
  • 11 Nov 2022
Topic Review
Open VOGEL
OpenVOGEL is a collection of free open source computer packages intended for the simulation of aerodynamic problems through the Unsteady Vortex Lattice Method and first order singularity panels (vortex rings, flat doublet panels and flat source/sink panels). The project provides a main application (named Tucan) that integrates all the packages in an interactive and intuitive way for final users. However, any other library can be linked to an external project without the need of a graphical toolkit. A console application has also been developed to provide the same calculation capability as Tucan but without graphical interface. This program extends the service to Linux users, since it is able to run under the Mono runtime without recompilation. All libraries and applicatioms are fully developed in the .NET framework using Visual Studio Express and they are published under General Public License, GPLv3. The OpenVOGEL project comprises the next set of libraries (originally developed by Guillermo Hazebrouck): Additionally, the project relies in the next third party libraries: A feature of the Open VOGEL project is that users can add their own models to the library, and expand that way the general capabilities of the software or adapt it for a specific purpose. In that sense, the software acts as a basic framework for research applications. Any university, research group or individual in the world is authorized to take the source code, modify it and release it under GPLv3 for further use in the aeronautical community. The idea behind this experimental way of working is that those who use the software for practical applications can directly benefit from what researchers are achieving, so that their results can be directly put into practice.
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  • 10 Nov 2022
Topic Review
Origins of Judaism
The origins of Judaism lie in the Bronze Age amidst polytheistic ancient Semitic religions, specifically Canaanite religion, co-existing with a syncretization with elements of Babylonian religion and of the worship of Yahweh reflected in the early prophetic books of the Hebrew Bible. During the Iron Age I, the Israelite religion became distinct from other Canaanite religions due to the unique monolatristic (proto-monotheistic) worship of Yahweh. During the Babylonian captivity of the 6th and 5th centuries BCE (Iron Age II), certain circles within the exiled Judahites in Babylon refined pre-existing ideas about monotheism, election, divine law and Covenant into a strict monotheistic theology which came to dominate the former Kingdom of Judah in the following centuries. From the 5th century BCE until 70 CE, Israelite religion developed into the various theological schools of Second Temple Judaism, besides Hellenistic Judaism in the diaspora. Second Temple eschatology was significantly influenced by Zoroastrianism. The text of the Hebrew Bible was redacted into its extant form in this period and possibly also canonized as well. Rabbinic Judaism developed during Late Antiquity, during the 3rd to 6th centuries CE; the Masoretic Text of the Hebrew Bible and the Talmud were compiled in this period. The oldest manuscripts of the Masoretic tradition come from the 10th and 11th centuries CE; in the form of the Aleppo Codex of the later portions of the 10th century CE and the Leningrad Codex dated to 1008–1009 CE. Due largely to censoring and the burning of manuscripts in medieval Europe the oldest existing manuscripts of various rabbinical works are quite late. The oldest surviving complete manuscript copy of the Babylonian Talmud is dated to 1342 CE.
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  • 10 Nov 2022
Topic Review
Sex Differences in Humans
Sex differences in humans have been studied in a variety of fields. In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome, the type of gonads, the sex hormones, the internal reproductive anatomy (such as the uterus), and the external genitalia. Genetic sex is determined solely by the presence or absence of a Y chromosome. A child's presumed sex is determined at birth by observation of the external genitalia. Sex differences generally refer to traits that are sexually dimorphic. A subset of such differences is hypothesized to be a product of the evolutionary process of sexual selection.
  • 3.1K
  • 16 Nov 2022
Topic Review
Radix-16 Floating Point
IBM hexadecimal floating point is number representation. IBM System/360 computers, and subsequent machines based on that architecture (mainframes), support a hexadecimal floating-point format (HFP). In comparison to IEEE 754 floating-point, the IBM floating-point format has a longer significand, and a shorter exponent. All IBM floating-point formats have 7 bits of exponent with a bias of 64. The normalized range of representable numbers is from 16−65 to 1663 (approx. 5.39761 × 10−79 to 7.237005 × 1075). The number is represented as the following formula: (−1)sign × 0.significand × 16exponent−64.
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  • 16 Nov 2022
Topic Review
Goonda
"Goonda" is a term in Indian English, Pakistani English, and Bangladeshi English for a hired thug. It is both a colloquial term and defined and used in laws, generally referred to as Goonda Acts.
  • 1.5K
  • 10 Nov 2022
Topic Review
Atomic Units
Atomic units (au or a.u.) form a system of natural units which is especially convenient for atomic physics calculations. There are two different kinds of atomic units, Hartree atomic units and Rydberg atomic units, which differ in the choice of the unit of mass and charge. This article deals with Hartree atomic units, where the numerical values of the following four fundamental physical constants are all unity by definition: In Hartree units, the speed of light is approximately [math]\displaystyle{ 137 }[/math]. Atomic units are often abbreviated "a.u." or "au", not to be confused with the same abbreviation used also for astronomical units, arbitrary units, and absorbance units in different contexts.
  • 8.9K
  • 10 Nov 2022
Topic Review
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual processes by studying the effect on a subject's experience or behaviour of systematically varying the properties of a stimulus along one or more physical dimensions". Psychophysics also refers to a general class of methods that can be applied to study a perceptual system. Modern applications rely heavily on threshold measurement, ideal observer analysis, and signal detection theory. Psychophysics has widespread and important practical applications. For example, in the study of digital signal processing, psychophysics has informed the development of models and methods of lossy compression. These models explain why humans perceive very little loss of signal quality when audio and video signals are formatted using lossy compression.
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  • 10 Nov 2022
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