Soltan Ahmad Shah Qajar (1909-1925) was the last ruling Shah. Among many other members of the Qajar family are
Zenwalk Linux
Zenwalk (formerly Minislack), or Zenwalk Linux, is a Linux distribution started by Jean-Philippe Guillemin. It was at first based on Slackware. Since its creation, the distribution has become very different from Slackware while still still being able to use its binary packages. Zenwalk aims to be a Linux distribution with many uses by focusing on Internet applications, multimedia and programming tools.
The Zenwalk Project aims to create a Linux operating system that can be used on old and slow computers through the use of the latest software available for a stable release, optimization for a specific processor architecture to increase execution speed, and introduces a very powerful package management system with dependency resolution.
There are four main versions of Zenwalk:
Zenwalk (full version ~ 420 MB iso download) is a distribution aimed at mainstream desktop use. Designed to be a stand-alone operating system, it installs to the hard drive by way of a ncurses-based installer. It includes all of the officially released software packages that are deemed most useful for their tasks. This collection may change with every release.
Zenwalk Core (~ 230 MB iso download) is a Zenwalk system built with customization in mind. Released with no X Window System binaries, its aim is to allow a skilled user to build a system fit for his or her needs. The project's lead developer is Emmanuel Bailleul.
ZenLive (~ 476 MB iso download) is a Zenwalk system built on a Live CD design. ZenLive follows the progress made by the full Zenwalk system closely, thus mirroring the version number, and attempts to stay true to the original distribution's goals. In addition, it includes all of the necessary libraries and applications to develop and compile software, a particularly rare feature in Live CD distributions. Project members include Pierrick Le Brun, creator, Mauricio Tricoli, project lead, and Michael Verret, artwork.
Zenserver (~ 263 MB iso download) is a Zenwalk Core-derived system specifically designed for servers. The main goals are to create a secure, reliable, easy to use, easy to configure, expandable and dependable server operating system, in the best Zenwalk tradition. The distribution development team is led by Teran McKinney.
There are currently four Zenwalk-based distributions:
Thermodynamic equilibrium
In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, radiative equilibrium, and chemical equilibrium. The local state of a system at thermodynamic equilibrium is determined by the values of its intensive parameters, as pressure, temperature, etc. Specifically, thermodynamic equilibrium is characterized by the minimum of a thermodynamic potential.
Thermodynamic potential
In thermodynamics, thermodynamic potentials are parameters associated with a thermodynamic system and have the dimensions of energy. They are called "potentials" because in a sense, they describe the amount of potential energy in a thermodynamic system when it is subjected to certain constraints. The different potentials correspond to different constraints to which the system may be subjected. The four most common thermodynamic potentials are:
where "T" = temperature, "S" = entropy, "p" = pressure, "V" = volume. The Helmholtz free energy is often denoted by the symbol "F", but the use of "A" is preferred by IUPAC (See Alberty, 2001). formula_1 is the number of particles of type "i" in the system. For the sake of completeness, the set of all formula_1 are also included as natural variables, although they are sometimes ignored.
Thermodynamic potentials are very useful when calculating the equilibrium results of a chemical reaction, or when measuring the properties of materials in a chemical reaction. The chemical reactions usually take place under some simple constraints such as constant pressure and temperature, or constant entropy and volume, and when this is true, there is a corresponding thermodynamic potential which comes into play. Just as in mechanics, the system will tend towards lower values of potential and at equilibrium, under these constraints, the potential will take on an unchanging minimum value. The thermodynamic potentials can also be used to estimate the total amount of energy available from a thermodynamic system under the appropriate constraint.
Thermal efficiency
The thermal efficiency (formula_1) is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example.
The input, formula_2, to the device is heat, or the heat-content of a fuel that is consumed. The desired output is mechanical work, formula_3, or heat, formula_4, or possibly both. Because the input heat normally has a real financial cost, a memorable, generic definition of thermal efficiency is
formula_5
From the first and second law of thermodynamics, the output can not exceed what is input, so
formula_6
When expressed as a percentage, the thermal efficiency must be between 0% and 100%. Due to inefficiencies such as friction, heat loss, and other factors, thermal efficiencies are typically much less than 100%. For example, a typical gasoline automobile engine operates at around 25% thermal efficiency, and a large coal-fueled electrical generating plant peaks at about 36%. In a combined cycle plant thermal efficiencies are approaching 60%.
When transforming thermal energy into mechanical energy, the thermal efficiency of a heat engine is the percentage of energy that is transformed into work. Thermal efficiency is defined as
formula_7,
or via the first law of thermodynamics to substitute waste heat rejection for the work produced,
formula_8.
For example, when 1000 joules of thermal energy is transformed into 300 joules of mechanical energy (with the remaining 700 joules dissipated as waste heat), the thermal efficiency is 30%.
For an energy conversion device like a boiler or furnace, the thermal efficiency is
formula_9.
So, for a boiler that produces 210 kW (or 700,000 BTU/h) output for each 300 kW (or 1,000,000 BTU/h) heat-equivalent input, its thermal efficiency is 210/300 = 0.70, or 70%. This means that the 30% of the energy is lost to the environment.
An electric resistance heater has a thermal efficiency of at or very near 100%, so, for example, 1500W of heat are produced for 1500W of electrical input. When comparing heating units, such as a 100% efficient electric resistance heater to an 80% efficient natural gas-fueled furnace, energy prices must be compared to find the lower cost.
Heat pumps, refrigerators, and air conditioners, for example, move heat, rather than convert it, so other measures are needed to describe their thermal performance. The common measures are the coefficient-of-performance (COP), energy-efficiency ratio (EER), and seasonal-energy-efficiency ratio (SEER).
The Efficiency of a Heat pump (HP) and Refrigerators (R)*:
formula_10
formula_11
formula_12
If temperatures at both ends of the Heat Pump or Refrigerator are constant and their processes reversible:
formula_13
formula_14
The 'thermal efficiency' is sometimes called the energy efficiency. In the United States, in everyday usage the SEER is the more common measure of energy efficiency for cooling devices, as well as for heat pumps when in their heating mode. For energy-conversion heating devices their peak steady-state thermal efficiency is often stated, e.g., 'this furnace is 90% efficient', but a more detailed measure of seasonal energy effectiveness is the Annual Fuel Utilization Efficiency (AFUE).
Thermodynamic state