1、40.1CHAPTER 40COMPUTER APPLICATIONSComputer System Components and Technologies 40.1Networking Components . 40.5Internet and Applications 40.7HVAC Software Applications 40.9Monitoring and Control 40.17Wireless Communication 40.19OMPUTERS are used in a wide variety of applications in theC HVAC industr
2、y. Rapid technological advances and the de-creasing cost of computing power, memory, and secondary storagehave changed many aspects of the HVAC industry. New HVAC de-sign tools allow optimal solutions to be found in engineering appli-cations. Building operations benefit from low-cost networking toac
3、hieve multivendor control system interoperability. Consulting en-gineers can search manufacturers equipment and specifications in-teractively over the Internet. Designers can collaborate from remotelocations. More powerful applications that are also easier to use arenow affordable by a wider segment
4、 of the industry; many HVACcalculations, such as heating and cooling loads, can be performedeasily and automatically.Business applications and infrastructure have also positivelyaffected the HVAC industry. Open communications standards andinternetworking allow fast, efficient communications througho
5、utcompany and industry circles. HVAC design, manufacture, installa-tion, and maintenance functions benefit as businesses build comput-ing infrastructure through corporate information services (IS) orinformation technology (IT). Many advances in the business commu-nity have been adopted by the HVAC i
6、ndustry as de facto standards.1. COMPUTER SYSTEM COMPONENTS AND TECHNOLOGIESBecause of rapid advances in computer technology, computersoffer tremendous power at very low cost. However, the total cost ofownership of a personal computer is not limited to the cost of thecomputer hardware. Software, net
7、work connectivity, support, andmaintenance expenses quickly surpass the initial cost of hardware.Selecting a computer platform includes a wide variety of issues,such as Analysis of application needsCorporate computer support architecture and standardsVendor support, including guaranteed response tim
8、eCentral processing unit (CPU) power, random-access memory(RAM), and secondary or hard disk storage capacitySystem compatibility and interoperability between vendorsEase of use and required trainingData backup strategy: how will the data on the computer be restored in the event of a system failure?S
9、ecurity issues: what data will be accessible, and how will databe protected from unauthorized access?Network communications capability and compatibilityTechnical support live and/or online, including driver updatesupportCost/benefits comparisonInformation system infrastructure/interoperability requi
10、rementsTechnology reliability and obsolescenceTotal cost of ownershipVirtually all brand-name personal computers now have more thanenough speed for basic business applications such as word process-ing and spreadsheets. Personal computers differ in their ability tohandle multimedia graphics and sound
11、, which are useful in advancedsoftware applications.An information system comprised of computer networks dependson the ability of computers to communicate with each other in a stan-dard architecture. Technological advances have resulted in computersystems becoming obsolete in less than five years. T
12、herefore, it isimportant to plan for compatibility with future business computerrequirements. Software and hardware must match the needs of theuser, and be consistent with the business system architecture.System architecture standards from organizations such as the In-stitute of Electrical and Elect
13、ronics Engineers (IEEE), the AmericanNational Standards Institute (ANSI), and the International Organi-zation for Standardization (ISO) have resulted in well-defined stan-dards such as Ethernet, TCP/IP, and HTTP, further described in thesection on Networking Components. The combination of popularsta
14、ndards has resulted in network and Internet accessibility from lo-cal computers.1.1 COMPUTER HARDWAREHardware is the physical equipment (electronic parts, cables,printed circuit boards, etc.) that provides the foundation for thesoftware to run. Hardware processing power has increased dramati-cally,
15、such that the average business system provides much morecapacity than the average user needs. Specialized tasks, however,often require specialized hardware.Mainframes are large, expensive computer systems that servethe majority of large-scale business and technical needs. Mainframecomputers best ser
16、ve large nationwide databases, weather predic-tion, and scientific modeling applications. They support many userssimultaneously, and are usually accessed over a network from a per-sonal computer (PC). More powerful mainframes are called super-computers.Personal computers (PCs) are desktop computers
17、tailored toindividual user needs, and provide much more convenient access tocomputing resources than the traditional mainframe. PCs are used ina wide variety of information-gathering, communication, organiza-tion, computation, and scheduling roles.PC servers allow access to files and data on a netwo
18、rk. PC serv-ers are a special class of computers that support large amounts ofmemory, fast connection speed to the network, large disk storage foraccess of many files, and applications designed to be usable fromother computer systems. Because system reliability is critical, thereare additional featu
19、res such as better construction, componentredundancy, and removable hard drives.Workstations are application-specific computers serving special-ized needs such as computer-aided design (CAD) and manufacturingThe preparation of this chapter is assigned to TC 1.5, ComputerApplications.40.2 2015 ASHRAE
20、 HandbookHVAC Applications (SI)(CAM), product design and simulation, mapping geographic infor-mation system (GIS), or specialized graphics design. Workstationshave greater processing power and graphical display capabilitiesthan personal computers, and may also have other improvementsfound in PC serv
21、ers.Clusters are several computers organized to work together.Clusters of PCs can approach the computing power of a mainframeat a fraction of the cost, if efficient application software is available.Clusters of workstations can provide more computing power thaneven the largest mainframe. Clusters of
22、 mainframes can be ex-tremely powerful tools.Minicomputers are medium-sized business computer systemsthat serve medium to large application needs. Minicomputers havebeen used to economically scale applications that have grown toolarge for PC servers. Many small business e-commerce applicationshave m
23、oved to the minicomputer platform.A web server is a PC server, minicomputer, or mainframe thatstores and distributes web-based information; it is typically used todistribute documents and other information across the Internet.Laptop computers are smaller, battery-powered personal com-puters optimize
24、d for light weight and portability. Compared to asimilarly priced personal computer, laptops are generally slowerand have fewer features, though they generally include most basicfeatures found in a desktop computer. A smaller, lighter laptop com-puter is called a notebook or netbook.Palmtop computer
25、s serve a specialized niche, allowing accessto some of the same information available from a laptop, but in amuch smaller package. Palmtops may have no keys, or very smallkeys that are much smaller than the standard keyboard.Personal digital assistants (PDAs) support limited functional-ity of laptop
26、 computers in a notecard-sized format. A typical inter-face method is a stylus with a graphical touch-sensitive screen;standard functions include a calendar, address book, e-mail, and acalculator. Options include synchronizing hardware to uploadaddress lists or e-mail to a PC, and a modem or wireles
27、s card for por-table Internet access. Some models combine the functionality of aPDA with a cell phone and a digital camera.Smartphones are mobile phones that offer advanced computingability and connectivity. Smartphones run complete operating sys-tem software, providing a platform for application de
28、velopers, andare able to run many different types of software applications, includ-ing those specific to HVAC engineering. The advantages of smart-phone applications over desktop applications are that they are simpleto use and can easily be deployed in the field for quick calculations.Calculators an
29、d organizers are available usually for fixed arith-metic functions and, on the high end, programmable applications.This hardware format is typically inexpensive and portable, but soft-ware is typically proprietary. Laptops, palmtops, and PDAs havechallenged the advantages of calculators and organize
30、rs.1.2 COMPUTER SOFTWARESoftware is computer instructions or data that can be stored elec-tronically in storage hardware, such as random access memory(RAM), or secondary storage such as hard disk drives, DVDs, or CDs.Software is often divided into two categories:Systems software includes the operati
31、ng system and utilities asso-ciated with the operating system, such as file copying.Applications software includes the programs used to do the userswork, such as word processors, spreadsheets, or databases. HVAC-specific programs belong to the applications software category.Operating SystemsThe oper
32、ating system (OS) is the basic control program thatallows execution and control of application software. Operatingsystems (system software) also provide a common environment forapplications to use shared resources such as memory, secondarystorage (e.g., hard disk storage), processing time, network a
33、ccess,the keyboard, graphic display environments, desktops, file ser-vices, and printer services. Application software must be selectedfirst; that decision will typically limit the hardware computer plat-form and OS.Utility SoftwareUtility programs perform a wide variety of organizing and data-handl
34、ing operations such as copying files, printing files, file man-agement, network analysis, disk size utilities, CPU speed tests,improving security, and other related operations. Most utilities per-form one or two specific functions.Compression Software. These utilities compress and archivedata files
35、in a standard format, such as ZIP. Compression utilitiesallow files and file systems to be compressed, making the transfer ofinformation and files much more efficient without any loss of con-tent or data. These utilities are valuable when file size is important,such as transmitting files over a limi
36、ted-bandwidth communicationsystem, and for archival purposes. A typical compression ratio fortext files is 3:1. E-mail attachments are often compressed.Antivirus Software. An important software package for mostcomputer systems is antivirus software (see the section on E-mail,Viruses, and Hoaxes). An
37、tivirus software detects, quarantines,repairs, and eliminates files that contain viruses. A computer virusmay take various forms and is commonly attached invisibly to aword-processed or e-mailed document. Antivirus software is imper-ative when a computer is accessing Internet-based information.Antiv
38、irus software must be updated frequently to be able to catchnew viruses. Updates are often available for free after purchasingantivirus software.Antispyware Software. Spyware is a type of program that sendsinformation from your computer to another computer, usually withmalicious intent. It may send
39、passwords, credit card numbers, or anyother information that is typed into your computer. Antispywaresoftware will detect spyware and remove it.Firewall Software. A firewall is a utility that controls and limitsall network communications going from or to your computer. Witha firewall, only programs
40、with permission are allowed to communi-cate over the network. This should stop spyware and other similarmalicious programs. Also, a firewall limits the communications itaccepts over the network, which acts against other types of attacks.A large organization should have a firewall separating their en
41、tirenetwork from the Internet, but it is still important to have a firewallon each PC.Back-Up Software. The ability to recover from a massive failuresuch as a successful virus attack, accidental deletion of files, flood,fire, hardware (especially hard disk) failure, and other inevitabledisasters is
42、extremely important. Typically, information service (IS)computers use a rotating digital tape back-up strategy that performsmassive back-ups of network resources. Individual computers maynot be included in these back-ups, so regularly scheduled back-upsmust be performed. A relatively inexpensive way
43、 to back up smallamounts of data is to store data files and documents in a compactdisk recordable (CD-R) format, which allows roughly up to 700 MBof storage at low cost. Digital versatile disks (DVDs) promiseroughly 10 times the storage capacity of CD-R. Tape back-up pro-vides an extremely low cost
44、per megabyte stored and is useful ifquick access and retrieval of individual back-up files is not an issue.Back-ups should be stored in a secure location away from the com-puter system. There are two basic types of back-ups: complete, inwhich all files are backed up, or incremental, in which only fi
45、leschanged since the last back-up are stored. A typical strategy is toperform a complete back-up once a week or month, and an incre-mental back-up every day.Computer Applications 40.3Application SoftwareMost useful application software falls into one of these categories:Word Processing. Word process
46、ing applications are used fortasks that range from creating simple printable documents to pro-viding products for advanced enterprise-level electronic distributionand publishing systems. Features may include automatic text lay-out, spellchecking, printing, index and table of contents generation,simp
47、le graphics, and the ability to save files in a variety of formatssuch as rich text format (RTF), hypertext markup language(HTML), plain text, or American Standard Code for InformationInterchange (ASCII). Most word processors allow the user to viewthe output before printing.Specification Writing. A
48、useful extension to word processors isapplication software to create specifications for the consulting engi-neer. Features include ensuring selectable sections for creatingdesired features, and consistent naming of materials, specifications,and processes or sequences.Specification software can save
49、time by allowing the reuse of sec-tions from a master specification, along with previously developedspecification details, sometimes with small changes. Specificationtools are most useful in situations that do not require completely newspecifications from project to project.Desktop Publishing. This is a specialized class of word proces-sors with high-end, professional text and graphics layout features.Desktop publishing systems have been extended to incorporateprofessional-quality graphical images, many different styles of textand fonts, and special effects such as color fading, shadowin
