A PEEP INTO BEING IN COMPANY OF ELEMENTS OF NATURE

A photoessay of being with elements of nature from trekking at sunderdunga glacier in uttaranchal to diving off kavarati in laccadive island to surfing at bagga beach goa to sailing in shenzhen off south china sea to hiking in skaftafell sanctury of iceland to skiing in polar ice cap of greenland to climbing in solang valley in himachal and alpine expedition to kanchenjunga sanctury in sikkim.

PIPING SYSTEM FABRICATION AND SURVEY: A SHIPBUILDING PERSPECTIVE

INTRODUCTION
1. If one recounts the development of machines from steam engine to modern day gas turbine engine, one would observe, that all machines have their weakness in the unannounced bleeding of their veins and arteries i.e. it’s piping network. However piping industry has kept pace with changes in all other shop floor production methods. The new industry tool in the hands of a system manufacturer or repairer/surveyor, to reduce downtime and over-maintenance of marine equipment, by means of a robust and reliable piping system is elucidated in the succeeding paragraphs.

TRENDS IN PIPE MANUFACTURING
2. The manufacturing of a piping system consists of four major sub processes namely; bending, flanging, branching and welding/brazing. The automation of these sub-processes that has occurred in shipyards, to help in achieving consistency in quality of production, enhances speed and reduces the inventory of ferrous and non ferrous castings is amplified below:

3. Pipe Bending. The manual intensive process used for pipe bending, by filling the entire pipe with sand tightly and bending it to the required curvature by cold bending, used to take about two man-days and in case of hot bending about four man-days. But with the help of new 100 CNC 3 X pipe bending machine, it is now a matter of few hours for a pair of skilled pipe fitters. This machine can do cold bending of steel and Cu-Ni pipes of ODs, as large as 114.3 mm along with pipe thickness of 4.85 mm. The approximate cost of such machines is about Rs. 84.3 lakh. One such commercial machine manufactured by M/s Electro-pneumatic and hydraulic India Pvt. Ltd. Mumbai, is used in the construction for new ships. The advantage of this bending machine is that, the problems of residual stress, formation of folds on completion and pin holes at pipe bends, faced with manual bending method has been reduced. Further, pipes of large diameter and thickness do not require an additional inventory of pre-casted elbow pieces to be kept standby for use at bends.

4. Pipe Flanging. The making of flanges for any pipe is a time consuming process entailing, flange-casting, machining and erection of template/ jig followed by welding of flange to the pipe. A minimum of three man-days were required for making a flanged pipe. But technology infusion by means of the new T drill F-200 flanging machine, has shrunk the process time to less than an hour by deploying two skilled machinists only. This machine can make flanges up to 219.1 mm OD, the maximum thickness allowable for cold flanging is 5 mm and 8 mm for hot flanging. The purchase price of the equipment is about Rs.1.5 crore. The aid of a flanging machine manufactured by M/s T Drill OY company of Finland, has hastened the pace of production at shipyards. The use of this machine removes the intermediate step of flange welding, flange neck was a perennial source of leakage due to weld erosion.

5. Pipe Branching. The branching of a piping system, earlier entailed procurement of pre-casted T-pieces. But with help of new TEC-150 branching machine, the entire inventory for casted pipe T pieces can be done away with. The latest machine can make branching holes by extrusion and welding for pipes up to 420 mm OD for ferrous as well as non ferrous application. The machine manufactured by M/s T Drill OY Company of Finland costing about Rs. 2.0 Crore, is the latest addition to production floor for the new construction activity at shipyards. The use of this machine removes the use of a casting prone to pin holes due to porosity in casts and bimetallic corrosion due to difference in system pipe and T piece metallurgy.

TRENDS IN PIPE SURVEY
6. The manufacturing of pipes is just a beginning in the long journey of fault free machinery initiatives. The main part of the entire endeavor for enhanced reliability is early fault detection in post manufacturing stage onboard ships. In actual terms the process of fault detection is much more difficult since it is akin to ‘finding a dead person’s disease, without actually digging his grave’. The cutting edge technology for marine application in ILI (In Line Inspection) use non-intrusive methods of NDE (Non-destructive examination). The site practices for survey are influenced by benchmarked standards of API(American Petroleum Institute), ASTM (American Society for Testing Methods), ABS (American Bureau of shipping) and ASME (American Society for Mechanical Engineer). The three major NDE methods, practically usable in our own Indian Naval operating domain are discussed below:

7. Acoustic Emission Test. Acoustic Emission Test (AET) is a process whereby an elastic wave, in the range of ultrasound usually between 20 KHz and 1 MHz, is generated by the rapid release of energy from the source within a material. The elastic wave propagates through the solid to the surface, where it can be recorded by one or more sensors. The sensor is a transducer that converts the mechanical wave into an electrical signal. In this way information about the existence and location of possible sources is obtained. AE analysis is a useful method for the investigation of local damage in materials. One of the advantages compared to other ND techniques is its ability to observe damage processes during the entire load history without any disturbance to the specimen. The only disadvantage of AE is that it can only estimate the damage in the material and approximate life of the components qualitatively, not quantitatively. Moreover, service environments are generally very noisy, and the AE signals are usually very weak. Thus, signal discrimination and noise reduction are very difficult, which is extremely important for successful AE applications. This application is aptly suited for critical hydraulic and pneumatic systems (High pressure) used in main propulsion, steering and weapon controls, where pre-emptive change of possible cause of pipe failure is of paramount significance for operational readiness. A majority of HP pipes in pneumatic and hydraulic systems are prone to failure due to stress in pipes.

8. Magnetic Flux Leakage. Magnetic flux leakage (MFL) is a magnetic method of non-destructive testing that is used to detect corrosion and pitting in steel structures, most commonly in pipelines and storage tanks. The basic principle is that a powerful magnet is used to magnetize the steel. At places where there is corrosion or missing metal, the magnetic field "leaks" from the steel. In an MFL tool, a magnetic detector is placed between the poles of the magnet to detect the leakage field. Analysts interpret the chart recording of the leakage field to identify damaged areas and to estimate the depth of metal loss. Figure below illustrates the basic principle of the MFL method. A magnet mounted on a carriage induces a strong magnetic field in the plate or pipe wall. In the presence of a corrosion pit, a magnetic flux leakage field forms outside the plate or pipe wall. An array of sensors is positioned between the magnet poles to detect this flux leakage. The sensors are usually Hall Effect devices or coils; there are advantages and limitations with either type of sensor. The use of MFL technique is a better tool over visual examination, for gauging health of main fuel supply trunking and the fire-main system/ ring-main in alleyways during NR/MR of a ship. The main trunking of fuel and fire-main lines are critical pipes most prone to internal corrosion/ metal erosion.

9. Ultrasonic testing. Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements and material characterization. A typical UT inspection system consists of several functional units, such as the receiver, transducer, and display devices. A receiver is an electronic device that can produce high voltage electrical pulses. Driven by the receiver, the transducer generates high frequency ultrasonic energy. The sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen.. Figure below illustrates a simple UT set-up using the pulse-echo principle and a twin crystal probe. In this configuration one crystal acts as transmitter and the other as the receiver. The transmitter is isolated from the receiving circuits so that the A-scan display is freed from the presence of a transmission signal. As a result the transmission pulse does not obscure the first back wall echo when testing relatively thin areas of plate or pipe. Ultrasonic Inspection is a very useful and versatile NDT method. Some of the advantages of ultrasonic inspection that are often cited are that, It is sensitive to both surface and subsurface discontinuities, the depth of penetration for flaw detection or measurement is superior to other NDT methods.

CONCLUSION
10। The plumbing industry outside shipyards is changing and so are the shipyard’s, engaged in construction of new ships for Indian Navy. Our Naval Dockyards, who are the custodians of maintenance for the 21st generation ship/s with new methods of piping fabrication, have to generate domain awareness towards this change in method of piping erection/ survey. An audit of our ability to augment the skill-set of the apprentice/ artificers, to keep pace with new methods of pipe manufacture/ inspection, in tandem with efforts to establish shore installations with new generation machines/ tools for piping departments of ship repair yard, is the need of the hour.
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Acknowledgement :
1. Comments on AET by Cdr S Mujumdar Ex Senior Manager at Systems Department Naval Dockyard Mumbai.
2. Comments on piping manufacture by Mr. M RoyChowhary; Consultant to M/s GRSE.
3.Comments on piping trends in marine industry by Cdr (Retd) A Bandhopadhyay at M/s ABG Shipyard.

References:
1.Detection of Mechanical Damage using the Magnetic Flux Leakage Technique by Mr. L. Clapham, Mr. V. Babbar and Mr. James Byrne. Queen’s University, Kingston, Ontario, Canada.
2.The Pipeline Defect Assessment Manual by Mr. Andrew Cosham & Mr. Phil.Hopkins at Proceedings Of IPC-2002: International Pipeline Conference 29 September - 3 October, 2002; Calgary, Alberta, Canada.
3. A Comparison of the Magnetic Flux Leakage and Ultrasonic Methods in the Detection and Measurement of Corrosion Pitting in Ferrous Plate and Pipe by Mr. J. C. Drury I.Eng. M.Inst. NDT.
4. American Petroleum Institute; Standards 570, 574, 578and 579.
5. American Society for Testing Methods; NDT Standards volume 03.03.
6. American Bureau of Shipping HSNC rules from section 4-6-2 for metallic pipes.
7. American Society for Mechanical Engineer; Spec no B31.3 for process piping and Section V for NDE.
8. QAP of Plumbing systems for New construction ships at WOT(Kol).

NAVAL COLLEGE SHARES BURDEN OF PAY COMMISSION

As I Google ‘Indian Navy’ on the internet, the hyperlinks to Naval College of Engineering and Sixth Pay Commission catch my eye. I wonder at the timing of my college’s Golden Jubilee being in news, at the same juncture, as hectic parleying for the Sixth Pay Commission is peaking in the media. Is it irony then, that their paths-meet? Pay Commission trying to attract best talent into it’s fold and NCE grooming the aspiring talent standing at it’s portal? So, while these current issues grab eyeballs of opinion makers, I feel tempted to steal mind’s of decision makers in Navy.
The technological and intellectual milieu, for places of learning, are churning and changing at breakneck speed. The Naval College of Engineering, as a feeder establishment for armed forces cannot remain insulated from the winds of change. If we reflect and take cue from the paradigm shift in the society we will see the gulf in our approach to the two concerns, firstly the NCE requirement to adapt to job relevance of the ever changing Navy and secondly it’s ability to live up to the aspiration of it’s budding engineers. These out of ordinary times, call for out of box thinking!
Fundamentally, relevance to job profile of a graduating engineer, is driven by HR concept to balance domain expertise and domain experience. Is there adequate work experience or exposure to Engineering standards like ASME, ASTM, BIS and ISO to budding engineers? Is there not a disconnect between the practicals in college and the practices onboard ships that need to be bridged and need not wait till MESC.?
Further, an engineer in the making, at any other premiere institute, burns midnight oil to add skill sets to his resume by learning and applying industry tools for PDMS, PID, ERP and SCM. Our new corps of Engineer Officer have to be armed by NCE with skills beyond the smoke-stack technologies of the industrial age, available in abundance with our army of dockyard foremen and armada of artificers. As the saying goes ‘if the only tool you have is a hammer, all problems will look like a nail’.
Alvin Toffler in his book Revolutionary Wealth states: ‘Educationists who attempt to redesign old institutions face resistance and innovators who seek to create new institutions face skepticism. Nineteenth century gave us Universities, Twentieth century gave us Research, Twenty first century combined research and university to give us Think Tanks’. The halo of awe around all great institutions is built on combined excellence in Teaching, Training, Research and Consulting. I may sound like I’m ‘spoiling the party’, but why is Research assigned to the Design/Professional Directorates only and Consulting the exclusive preserve of Trial/Workup teams, in this era of seamless integration of resources? Naval College of Engineering has to question whether its audience is confined to fellow academicians, Indian Navy, or both? By involving in research and consultancy for contemporary shipbuilding/ship-repair issues NCE can evolve into ‘Think Tank’ and break into the Brand of Indian Ivy leagues.
The concept of NCE as a Brand brings the compass needle of discussion, back to the original teaser question raised; Naval College shares burden of Pay Commission-Is it a Pipedream ? The current focus on tangibles like pay, perks and service conditions, as the only way to attract young impressionable minds of this nation is a skewed approach. In this media savvy era where brand-building as an art has surmounted evangelism, even God cannot be sold to people if not packaged and branded properly. In the formative years at NCE, the college not only makes us an engineers, but also lays the foundation to the mettle, that forms the core of an officer’s self belief and self worth. This self worth, exuded by our sub-lieutenants and midshipman along with their parents and the image thus perceived by peers in society, is the most credible emissary of NCE. Hence the question, how does the College administration hasten this process of building up it’s brand image? The five pronged approach for increasing presence in the circles of aspiring engineers can be seen as:
· Set a target to feature within top ten ranking engineering colleges shoulder to shoulder with IITs. After all, if AFMC can do it in field of medicine why can’t we at NCE do so?
· Consistent publications by faculty staff and students in peer-reviewed journals, conferences outside Navy needs to be given impetus.
· Increase the collaboration between college and intelligentsia from industry and professional societies for sake of advancement in contemporary knowledge and practices.
· Set a milestone for being recognized as an Engineering college as per ‘Washington Accord-1989’ of developed nations. At present only a select few colleges in India satisfy the QRs. If we can adhere to STCW, why not Washington accord parity?
· When we will build a coalition of the willing, the alumni network has to be nurtured and strengthened to link past, present and future students on same level field. An officer with single nelson ringed on his shoulder should be able to relate/connect to an admiral with a double braid on his peak cap.

I sing the last lullaby to my pipe dream narrated here, taking strength from what I read in an editorial of USNI Proceedings, ‘the pages of this magazine are open to all, no senior officer holds title of any real estate in pages of Proceedings’. Arundhati Roy, the writer, has said ‘Take a position, have a point of view, I am all for being circumspect, discretion, prudence and tentativeness. But history has had episodes where discretion was euphemism for pusillanimity to changing status quo, when caution was actually cowardice to face change, when circumspection was really a kind of espousal of turf.’ The grooming of intellectual audacity of a thinker and kindling the controlled aggression of a doer is a soft skill that no pay commission will provide. But our alma matar definitely can inculcate it in our fresh crop of engineers, that’s my pipedream for Naval College of Engineering.

RE-ENGINEERING HABITABILITY ONBOARD SHIPS

INTRODUCTION
1.1 You may have heard of ‘work-from-home’. What about ‘make-office-your home’? Well, the sailing community is just that, because the crew of a ship is required to live at the workplace. A sailor is subjected to six degree of motions and is constantly exposed to artificial ambient conditions of temperature, noise, vibration and light. The cumulative effect of imbalance in this environment, affects human performance by increasing physical and mental fatigue, which may lead to increase in human errors.
1.2 Shipboard habitability encompasses systems and facilities that are required to satisfy the basic human needs of the crew. Comfort in habitability and high-performance level of human efficiency would emanate from acceptable conditions onboard ships in terms of physical and spatial characteristics, in tandem with indoor climate, noise and lighting set to DEF STAN or MIL STD specifications.
1.3 Habitability can be improved in leapfrogs by addressing shortfalls in accommodation design and ambient indoor climate. The challenge lies in upgrading and maintaining habitability conditions through the total life cycle of a ship.

CHALLENGES AHEAD
2.1 The primary focus of this paper is to identify the Operating Procedures that are recognized as successful practices in new construction activity, for implementation during ship refit. A general overview of the approach road ahead is elucidated below.
Accommodation
2.2 Accommodation criteria pertain to dimensional or physical aspects of spaces and open deck areas, where crew members eat, sleep, recuperate and engage in their daily activities. The chasm between the requirements and the realities onboard are enumerated as follows.
2.3 Aspirations of the Naval Crew with respect to living comfort have undergone a major phase shift with social changes and level of education. Incorporation of aesthetics and ergonomy-efficient layouts of the accessories and fittings is essential. The in-house modification on ships during MLU, could be done in consultation with professional bodies as National Productivity Council, Bureau of Energy Efficiency, National Institute of Design and the like, to achieve better synergy of form and function within the unique constraints of warships.
2.4 We need to initiate the process of vendor development program for complete internal compartment (common area/ living spaces/ machinery compartment) refurbishment, during NR/MR akin to the practice in new construction of ships and not leave it to ship staff to revive the ship post long periods of lay off. This target of total overhaul of the outfitting, requires thorough internal ground work of formulating exhaustive SOR, SOW and QAP. Only then can we correctly monitor and implement a project activity through its various stages of inspections i.e: PI, II. FI.
2.5 The usage of advance outfitting material for aesthetics needs to be institutionalized and implemented on refit ships, much like the present drive for indigenization of equipments. Macro level policy for enhancement of aesthetics and appeal need to be formulated and implemented during MLU of ships. A top down approach for introduction of newly developed advanced material like modular kitchens, labour-saving devices and automated vending machines is required. This evolution should not be driven only by SOC from individual ships.
2.6 Increase in size of the crew beyond the capacity of existing indoor climate system degrades habitability. Shore accommodation should be established for in-living crew at the base port. This would reduce the load on the ship, and wear and tear of onboard facilities would be curtailed. The cost of replenishment and maintenance of ship facilities is far beyond that of establishments on shore.
Ambient Environment
2.7 The ambient environmental factors that affect habitability are noise, indoor climate and dust in living spaces. If the ambient temperature, humidity and noise in the ship are not conducive or sub optimal, these become negative motivators for the crew. All efforts for aesthetic up-gradation become difficult to maintain beyond one operational cycle due to dirt, discoloration and bad odour.
2.8 Habitability of western design ships are flawed in the Indian conditions, due to the fact that these ships are designed against a climate datum of cold weather. The NES 102 considers 35 Degree Centigrade (Dry bulb) as the extreme ambient temperature. However the Indian peninsula experiences tropical temperatures of about 40 Degree Centigrade (Dry bulb). The ambient conditions used for design of air conditioning systems by professionals for the Indian market, are in the range of 38.4 to 42.8 Degree Centigrade (Dry bulb) vide Bureau of Indian Standards Specs No. 7896-1996. The feasibility of implementing Bureau of Indian Standard ambient condition vis-a-vis present practice of using British NES specs for ambient condition, calls for us to pause and put on our thinking hats. The replacement of old HVAC equipment during ABER proceedings of a ship, with a higher capacity plant, needs to be experimented with on old ships.
2.9 The knowledge domain, for checking AHU’s Total air change, air quantity flow and chill water flow balancing, with tools like Velo-meter & Flow-meter needs to be used to it’s hilt on naval ships. These references are as basic to acceptance trial in shipbuilding yards as the tolerance limit for ship’s shafting. But unfortunately, the reference values and practices for major equipment health monitoring have proliferated in fleet ships whilst AHU maintenance by Ventilation Maintenance Party has not evolved beyond routine cleaning of AHU filters. The practice of in-house training and then monitoring aforesaid mentioned AHU parameters is much needed for successful preventive maintenance of ambient conditions. A working model, similar to that evolved in ships for CBPM and SPM measurement of engineering and electrical equipments, is an apt example.
2.10 The weakest link in the complete chain of the HVAC systems, is the deteriorated state of ventilation trunking running through the ships. This labour intensive product requires a technological shot in the arm. Firstly, we need to benchmark all new fabrication and erection against the reference standard of SAMCA (Society for Air Movement Control Association). Secondly, the mechanical supply fans of the machinery compartment are either devoid of inlet filters or are in very bad material state in most ships. There is a need to have coarse dust arrestors for the polluted Indian conditions to stop ingress of dirt inside ship. Thirdly, the flow capacity of existing supply blowers of AHU can be augmented by fitting Variable Frequency Devices to cater for trunking loss in old ships. Lastly, Vacuum Indicator Gauges, for checking choking of trunking filters need to be retrofitted, downstream of the filters for timely obviation of reduced air supply.
2.11 Our men onboard ships deserve a peaceful and quiet place to recuperate after a hard day’s toil. A strict implementation of upper noise regime of 85 db prescribed in NO 19/07 for ambient sound conditions, is called for. A specific action point in this regard, is to enhance noise damping features of our manned spaces, by augmenting noise insulation and fitting better quality SV mounts for our fans motors. All ventilation related moving equipment should undergo audit for noise regime and be re-engineered during MLU, if found digressing from acceptable norms. The Shipwright School, INS Shivaji and INS Valsura need to train trial team representatives, in noise monitoring technique, in accordance with prevalent MIL STD-1474D and ABS Specs for crew habitability.

WAY AHEAD
3.1 All plans for addition of new systems, equipment, personnel or an altogether change in role demands on ships, need to be accompanied by analysis of impact on existing habitability facilities. Habitability therefore needs to be seen as one aspect vis-a-vis other changes introduced.
3.2 Procedure needs to be established to identify ships for habitability up-gradation program, based on years-in-service, deterioration in upkeep and the accumulation of habitability deficiencies, as noted by the trial teams.
3.3 A well-managed habitability adherence programme, steered at grass-root level, in fleet and flotillas, by a nodal trial agency, is essential to ensure that ships conform to the NO 19/07 for habitability. Habitability policy implementation needs to be checked and rechecked on a continuous basis and should not be seen as a Medium Refit based activity alone.
3.4 Funds under NMS need to be increased, to cater for a short range program, initiated, planned and scheduled by the ship. This program should consist of practical, workable, short-range projects based on the individual Commanding Officer's strategy for enhancement of living quarters and personnel service areas, onboard ship. The emphasis of this program should be on improvement of existing living conditions and quality of life, using ship's own resources in an operational cycle.
3.5 A formalized long range program too needs to be initiated, using fleet maintenance funds and services of Naval Dockyard, for the accomplishment of approved habitability upgrade alterations during NR/MR/MLU. This program would assign contractor/ dockyard services for re-hauling the design and human engineering aspects of old ships. Monitoring and overall management of such a project during execution could be routed through nodal agencies like MMT.

CONCLUSION
4. As Indian Navy grows into an expeditionary force, the bottleneck of habitability upkeep will become an ‘Achilles heel’ for the older ships on long overseas deployment. Today, we contend with sparkling 21st century ships, brow to brow with the inherited earlier-generation ships. These old war horses, though retro-fitted with multi-million dollar weapons, have non-commensurate living conditions for the aspiring crew, which is a case of ‘putting the cart before the horse’. The New Navy Order 19/07 is a timely step in the right direction, which needs to be precipitated, by giving it teeth at implementation level and monitoring of Key Result Areas at the Command level.
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Acknowldgement:
1. Critical Significance of Human Factors in Ship Design, by Thomas G. Dobie, M.D., Ph.D., FRAeS, Director, National Biodynamics Laboratory University of New Orleans.Proceedings of the 2003 RVOC Meeting, 8 – 10 October, 2003 Large Lakes Observatory, University of Minnesota.
2. Application of System Safety Process for Acquisition of Quieter Systems and Equipment, by Mark Geiger, MS, MSE, CIH, CSP CNO N09FB OPNAV Safety Liaison Office Naval Environmental Health Conference Hampton, Virginia 20 March 2007.
3. Something from Nothing: ATU Condensate, by Cdr AK Rohatgi and Cdr Shantanu Bose discussion published in Journal of Ship Technology, Vol 3. No. 2, J uly 2007, pp. 85-86
4. Airborne Noise Control - Design Considerations & Shipboard Prototype Trials, Cdr Anup Menon, Journal of Marine Engineering Jun 07.
5. Habitability and personal space in sea keeping Behavior by, J.M. Riola, M.Garcia de Arboleya , Journal of Maritime Reaserch, Vol III No.1,pp.41-54,2006 SEECMAR, Spain
References:
1. Requirements for Heat Exchangers for HM Surface Ships and Submarines, Ministry of Defence, Defence Standard 02-329, Issue 2 Publication Date 20 June 2005
2. Requirements for Accommodation in HM Surface Warships and Submarines, Ministry of Defence, Defence Standard 02-107 Issue 2 Publication Date 24 May 2002
3. Requirements for Air Conditioning &Ventilation Part 1 HM Surface Ships and Royal Fleet Auxiliaries, Ministry of Defence, Defence Standard 02-102 (NES 102), Issue 2 Publication Date 8 September 2000
4. Noise Limits Design Criteria Standard, Metric MIL-STD-1474d 12 February 1997 Superseding (See Section 6.4) Department Of Defense
5. Human Factors for Designers of Systems Part 16: Introduction and Manpower Domain Technical Guidance and Data
Ministry of Defence, Defence Standard 00-25, Issue 1 Publication Date 30 July 2004
6. Human Factors for Designers of Systems Part 17: Personnel Domain Technical Guidance and Data Ministry of Defence, Defence Standard 00-25, Issue 1 Publication Date 30 July 2004
7. Society for Air Movement Control Association, http:// www.amca.org/
8. ABS Guide For Crew Habitability On Ships, http:// www.eagle.org/