The term RISC dates from about 1980.[16] Before then, there was some knowledge that simpler computers can be effective (e.g., John Cocke at IBM Research), but the design principles were not widely described. Simple, effective computers have always been of academic interest, and resulted in the RISC instruction set DLX for the first edition of Computer Architecture: A Quantitative Approach in 1990 of which David Patterson was a co-author, and he later participated in the RISC-V origination. DLX was intended for educational use; academics and hobbyists implemented it using field-programmable gate arrays, but it was never truly intended for commercial deployment. ARM CPUs, versions 2 and earlier, had a public-domain instruction set and are still supported by the GNU Compiler Collection (GCC), a popular free-software compiler. Three open-source cores exist for this ISA, but were never manufactured.[17][18] OpenRISC is an open-source ISA based on DLX, with associated RISC designs, and is fully supported with GCC and Linux implementations, although it too has few commercial implementations.
Asi Profile Inventor Free 21
As of 2019[update], RISC-V International freely publishes the documents defining RISC-V and permits unrestricted use of the ISA for design of software and hardware. However, only members of RISC-V International can vote to approve changes, and only member organizations use the trademarked compatibility logo.[23]
Discussion has occurred for a microcontroller profile for RISC-V, to ease development of deeply embedded systems. It centers on faster, simple C-language support for interrupts, simplified security modes and a simplified POSIX application binary interface.[38]
Financial Disclosure: Dr Gehrs has been a consultant for Bausch & Lomb and Genentech and has received research support as a clinical principal investigator or investigator from Eli Lilly, Novartis, Allergan, Alcon, Genentech, and Pfizer. The University of Iowa Department of Ophthalmology and Visual Sciences has received educational program support from Allergan, Alcon, and Novartis; and the University of Iowa holds patents and patent applications, of which Dr Hageman is an inventor and for which he receives royalties. Dr Hageman has consulted for Genentech, Pfizer, and OccuLogix; has received grants from Pfizer and Optherion Inc; and has a financial interest (stock ownership) in and was the chief security officer of Optherion Inc.
From the introduction of the Macintosh in 1984, with the 1984 Super Bowl advertisement to the more modern Get a Mac adverts, Apple has been recognized for its efforts towards effective advertising and marketing for its products. However, claims made by later campaigns were criticized,[201] particularly the 2005 Power Mac ads.[202] Apple's product advertisements gained a lot of attention as a result of their eye-popping graphics and catchy tunes.[203] Musicians who benefited from an improved profile as a result of their songs being included on Apple advertisements include Canadian singer Feist with the song "1234" and Yael Naïm with the song "New Soul".[203]
Many Apple Stores are located inside shopping malls, but Apple has built several stand-alone "flagship" stores in high-profile locations.[90] It has been granted design patents and received architectural awards for its stores' designs and construction, specifically for its use of glass staircases and cubes.[207] The success of Apple Stores have had significant influence over other consumer electronics retailers, who have lost traffic, control and profits due to a perceived higher quality of service and products at Apple Stores.[208] Due to the popularity of the brand, Apple receives a large number of job applications, many of which come from young workers.[205] Although Apple Store employees receive above-average pay, are offered money toward education and health care, and receive product discounts,[205] there are limited or no paths of career advancement.[205]
Following further campaigns by Greenpeace,[320] in 2008, Apple became the first electronics manufacturer to eliminate all polyvinyl chloride (PVC) and brominated flame retardants (BFRs) in its complete product line.[321] In June 2007, Apple began replacing the cold cathode fluorescent lamp (CCFL) backlit LCD displays in its computers with mercury-free LED-backlit LCD displays and arsenic-free glass, starting with the upgraded MacBook Pro.[322][323][324][325] Apple offers comprehensive and transparent information about the CO2e, emissions, materials, and electrical usage concerning every product they currently produce or have sold in the past (and which they have enough data needed to produce the report), in their portfolio on their homepage. Allowing consumers to make informed purchasing decisions on the products they offer for sale.[326] In June 2009, Apple's iPhone 3GS was free of PVC, arsenic, and BFRs.[322][327] All Apple products now have mercury-free LED-backlit LCD displays, arsenic-free glass, and non-PVC cables. All Apple products have EPEAT Gold status and beat the latest Energy Star guidelines in each product's respective regulatory category.[322][328]
In November 2011, Apple was featured in Greenpeace's Guide to Greener Electronics, which ranks electronics manufacturers on sustainability, climate and energy policy, and how "green" their products are. The company ranked fourth of fifteen electronics companies (moving up five places from the previous year) with a score of 4.6/10.[329] Greenpeace praises Apple's sustainability, noting that the company exceeded its 70% global recycling goal in 2010. It continues to score well on the products rating with all Apple products now being free of PVC plastic and BFRs. However, the guide criticizes Apple on the Energy criteria for not seeking external verification of its greenhouse gas emissions data and for not setting out any targets to reduce emissions.[330] In January 2012, Apple requested that its cable maker, Volex, begin producing halogen-free USB and power cables.[331]
The company's manufacturing, procurement, and logistics enable it to execute massive product launches without having to maintain large, profit-sapping inventories. In 2011, Apple's profit margins were 40 percent, compared with between 10 and 20 percent for most other hardware companies. Cook's catchphrase to describe his focus on the company's operational arm is: "Nobody wants to buy sour milk."[334][335]
The far field is the space outside the near field, meaning that the far field begins at a point at least one wavelength distance from the noise source. Standard sound level meters (i.e., type I and type II) are reliable in this field, but the measurements are influenced by whether the noise is simply originating from a source (free field) or being reflected back from surrounding surfaces (reverberant field).
A free field is a region in which there are no reflected sound waves. In a free field, sound radiates into space from a source uniformly in all directions. The sound pressure produced by the source is the same in every direction at equal distances from the point source. As a principle of physics, the sound pressure level decreases 6 dB, on a Z-weighted (i.e., unweighted) scale, each time the distance from the point source is doubled. This is a common way of expressing the inverse-square law in acoustics and is shown in Figure 4.
Free field conditions are necessary for certain tests, where outdoor measurements are often impractical. Some tests need to be performed in special rooms called free field or anechoic (echo-free) chambers, which have sound-absorbing walls, floors, and ceilings that reflect practically no sound.
The net result is a change in the intensity of the sound. The sound pressure does not decrease as rapidly as it would in a free field. In other words, it decreases by less than 6 dB each time the distance from the sound source doubles.
As sound power radiates from a point source in free space, it is distributed over a spherical surface so that at any given point, there exists a certain sound power per unit area. This is designated as intensity, I, and is expressed in units of watts per square meter.
The hierarchy of controls for noise can be summarized as: 1) eliminate or minimize noise exposure by installing equipment that produces less noise (e.g., buy-quiet programs), 2) prevent or contain the escape of noise at its source (engineering controls), 3) control exposure by changing work schedules to reduce the amount of time any one worker spends in the high noise area (administrative controls) or by changing practices such as distancing from noise-producing equipment (work practice controls), and 4) control the exposure with hearing protection. This hierarchy highlights the principle that the best prevention strategy is to eliminate exposure to hazards that can lead to hearing loss. Corporations that have started buy-quiet programs are moving toward workplaces where no harmful noise will exist. Many companies are automating equipment or setting up procedures that can be managed by workers from a quiet control room free from harmful noise. When it is not possible to eliminate the noise hazard or relocate the worker to a safe area, the worker must be protected with PPE.
Just because a surface area vibrates, it is not correct to assume it is radiating significant noise. In fact, probably less than 5% of all vibrating panels produce sufficient airborne noise to be of concern in an occupational setting. However, vibration damping materials can be an effective retrofit for controlling resonant tones radiated by vibrating metal panels or surface areas. In addition, this application can minimize the transfer of high-frequency sound energy through a panel. The two basic damping applications are free-layer and constrained-layer damping. Free-layer damping, also known as extensional damping, consists of attaching an energy-dissipating material on one or both sides of a relatively thin metal panel. As a guide, free-layer damping works best on panels less than -inch thick. For thicker machine casings or structures, the best application is constrained-layer damping, which consists of damping material bonded to the metal surface covered by an outer metal constraining layer, forming a laminated construction. Each application can provide up to 30 dB of noise reduction. 2ff7e9595c
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