J. N. Green | Open Library

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
in the course of guides you could enjoy now is technical drawing jn green below. Fox Valley Lutheran HS Fox Valley Lutheran High School COURSE WebRealistic. j-n-green-technical-drawing-free-pdf. 1/3. Downloaded from replace.me on. December 16, by guest. J N Green Technical Drawing Free Pdf.
 
 

technical drawing jn green.Technical Drawing for GCE & CSE : J. N. Green : : Blackwell’s

 

See all details. Next page. Brief content visible, double tap to read full content. Full content visible, double tap to read brief content. Help others learn more about this product by uploading a video! Customer reviews. How customer reviews and ratings work Customer Reviews, including Product Star Ratings help customers to learn more about the product and decide whether it is the right product for them.

Learn more how customers reviews work on Amazon. Top reviews Most recent Top reviews. Top review from the United States. There was a problem filtering reviews right now. Please try again later. Verified Purchase. This was purchased for my son who was just introduced to Technical Drawing without any additional support.

It proved quite useful and assisted him in understanding the steps required to draw the figures accurately. He also liked the size of the book One person found this helpful. See all reviews. Top reviews from other countries. Brilliant book for educating a beginner and refresh for those of us who have moved to computer based cad. It is well presented and each topic is easily understood. The exercises are well thought out and easily understood. My son likes it and has instilled an interest awY from the computer!

Report abuse. A good school text book. The program also features a sophisticated integrated plotter to plot location and estimated swath coverage. The Sea Scan PC enables the operator to view wide tracts of the seafloor by insonifying along the swath width and recording the strength of the echoes from the sea bottom.

The tow fish is towed just above the bottom of the seafloor. The tow fish continuously emits narrowly focused beams of sound perpendicular to the path of motion. The sound pulses pass through the water but are reflected from the seafloor and objects, such as wreck sites, on the seafloor.

The control comp uter records the echo signal strengths as they return and then draws the entire sonar record line on the screen. An image of the seafloor is built, line by line, as the sonar record line from each pulse of the sonar is returned and drawn on the screen. Marine Sonics, 7. The data is also shown in real time with along with the side scan trace and navigational information using the Sea Scan PC software.

This enables the operator to analyse and correlate magnetic anomalies with sonar imagery of the seabed. The magnetometer operates using proton precession and measures magnetic field intensity variations causes by ferrous deposits. The Garmin GPS was used to plot and record tracks of the survey vessel and position-fix targets. The DGPS was used to record land-based survey control points in order to geo-reference sites onto maps and charts.

Plan of the track of the survey vessel during course of the three-day survey. Figure 5 shows the tracks of the vessel during the various stages of the operation. Tracks were run east—west because of the nature of the seabed; it was easier to maintain a constant depth in this direction as the seabed generally sloped down to the south.

Some inconsistencies were noticed in the side scan traces particularly with the slipway track because the position of the side scan fish lay slightly behind the position of the GPS antenna thus causing discrepancies depending on which direction the vessel was travelling. Both side scan and magnetometer were deployed at the same time and data was recovered in separate channels in the Marine Sonic software, track in one channel, magnetic data in a second and a series of MST files representing the sonar image.

The side scan sonar was run on a single channel to simplify the recording and at the high frequency setting.

Swath widths were generally 50 or 75 m and the resolution was either about 5. The initial survey concentrated on the shallow water area where the dredging was to take place See Figure 6. Figure 8 shows the proposed area to be dredged superimposed over a sonar mosaic; the sea wall and the small groin to the east of the wall can be clearly seen.

The overall sonar survey is shown in Figure 9. The area with the sea grass is shown in Figure 10 where the beds of grass are clearly delineated. In the lower mid-left of this image structure and large objects can be seen. These are enlarged in Figure 11 which is a waterfall image of sonar trace, chains and scour can be seen in lower left and a small car tyre can be see in upper left. The slipway can be clearly seen in the bottom right of Figure Some alignment problems can be seen in this mosaic caused by the layback issues discussed above.

Detail of slipway can be seen in waterfall image Figure Bright objects on either side of slipway with dark acoustic shadows to left are the spit posts. In Figure 9 a number of small targets can be seen in the centre of the image, using SeaScanPC software it is possible to measure the height of these objects. Figure 7 shows two small objects with acoustic shadows to left, by measuring length of shadow against the height of tow-fish above sea bed it is possible to determine the approximate height of the object, in this case the object is 2.

Plan showing the proposed development and the proposed dredged area in white upper Figure In the sonar trace two small targets with acoustic shadows can be seen. The analog height measuring software places one of the three markers on the top of the object, one on the end of shadow and on the seabed mid left.

The analog shows how this operates in relation to the towfish lower right. Area to be dredged shown superimposed on side scan sonar trace mosaic. Total area covered by side scan sonar mosaic. Detail of soanr mosaic showing beds of sea grass and the outline of the sea wall and groin, Figure No te the left-hand side of image Figure Yellow markers represent 50 m intervals.

No te two bright spots with shadows extending downwards are the slipway guide dolfins for the slipway with their associated acoustic shadows. Figure 13 shows the extent of the mound representing the location of the demolished jetty. To the left the piles of the existing jetty can be seen, together with the propeller wash of the vessel from the previous run the small bubbles formed in the wash create marked trail that lasts for several minutes.

In the centre of the image, to the right of the existing jetty, debris can be seen. This is enlarged in Figures 15 and 16 showing what appears to be piles and jetty structural elements lying on the jetty mound and off to the northern side.

Software shows that the large piles lying on the seabed are about 6 m long, Figure Side scan trace of end of Town Jetty showing mound associated with the demolished Whalers Jerry and some of the debris. No te the small bright spots and lines upper left are the piles of the existing jetty.

Enlargement of debris field 17 Figure Side scan image of the Whalers Jetty mound on north side. The length of the linear feature in lower centre is 6. Magnetic contour plot of differential signal. Magnetic targets numbered 1 to 6. Because the magnetic survey was carried out over a number of hours on the three days, the diurnal field intensity that gradually changes over time creates problems in reducing the absolute background field intensity to a common value.

Therefore, as the signal was recorded digitally and integrated with position and time, it was possible to calculate the differential signal. Since the magnetometer records the field intensity once every second, the difference between each successive signal produces a differential reading, which is independent of the absolute value.

By downloading the data recovered in software by the Marine Sonic PC program, it was possible, using an Excel spreadsheet, to calculate the differential value between successive records. The magnetometer signal and the GPS location of the signal was then used to create a contour plot. Surfer was the program used, which creates a map showing the differential field intensity contours.

Unfortunately, Surfer does not have the ability to blank areas where no readings were made. As a result the program attempts to interpolate in these areas. In the Town Jetty survey, the magnetic effect of the slipway caused very large magnetic disturbances so the survey did not proceed into that area, although the effects were noted a considerable distance away.

In addition no recording were made in the northeast corner of the magnetometer plot because this was dry land. Therefore, when examining this plot, it is important to remember that everything on land should be ignored, everything in the region of the slipway should be ignored and the southwest corner near the jetty should also be ignored. The survey shows 5 main areas of magnetic disturbance: 1. Large magnetic target in deep water; 2.

Large area in the shallows with numerous small magnetic targets; 8. A series of magnetic targets to east of Town Jetty; 9.

A comp lex magnetic target in deep water at shoreward end of jetty; A comp lex of magnetic targets near old tug berth. It is likely that 3 represents small boat moorings or possibly small buried iron material, 4 is likely to be moorings relating a medium sized fishing boat, or moorings for vessels docked on Town Jetty to the west.

The anomalies 5 and 6 are unknown and will require investigation. Large anomalies 1 and 2 are also unknown, but possibly substantial iron objects such as large mooring anchors. Because of the very comp lex nature of the magnetic signals, it is very difficult to interpret. Anecdotal information suggests that the whole of the area is covered in mooring chains and anchors and these are likely to mask anything that is smaller such as a wooden vessel.

Table 3. These charts have been georeferenced against the modern aerial photographs so that it is possible to see the changes that occurred in the shoreline and the jetties. No t all the charts are of good quality, but there is enough topographical information to create a reasonable fit to the old and modern features hilltops, road intersections, etc. The figures have been created so that the historical charts are semi-transparent, and the modern features can be seen underneath.

The Figure 19, the chart shows the town jetty and two other jetties to the east. The shoreline is clearly indicated with the shallows, probably less than 2 feet shown dotted. The Figure 20, the chart shows the Town Jetty with the baths and the small jetty still on the shore. The Figure 21, the chart shows the extension to the jetty, with an additional new jetty with platform of some sort. The Figure 21 shows the extended jetty and extended baths with reclaimed land. Trace of the original shore line taken from a semi-transparent georeferenced chart and Figure Detail of the chart showing the Town jetty before the construction of the Whalers Jetty , overlaid on a modern aerial photograph.

Detail of the chart showing Town jetty with Whalers Jetty extension, overlaid on a Figure Trace with the semi-transparent chart removed. As part of this project an attempt was made to determine the approximate location of the Floating Dock that was abandoned sometime after the end of the First World War. A total of eleven historical photographs of Princess Royal Harbour were found showing the Floating Dock.

In some cases these photographs can be dated, for example, the American Fleet visited Albany in and the Floating Dock can be seen in the foreground Figure In many cases the Floating Dock can be seen against coastal features that allows a position line to be drawn.

A position line is basically a photo-transit; this is where two features in a photograph are aligned then a line can be extended from these two features the position line and this line can now be drawn on a map or chart.

If other features, such as the Floating Dock, lie on an extension of the position line then they will lie somewhere on the position line on the chart. If two or more different position line can be constructed, then the intersection of these lines on the chart gives the position of the object.

Two clear position lines, one coinciding with end of the Whalers Jetty with a point slightly east of Bridge Street Figure 24 and a second aligned with Seal Island and Mistaken Island Figure 23 give an approximate position of the mooring for the Floating Dock. A third line which is the project ion eastwards of the southern side of the old Jetty Baths Figure 25 give additional support to the location of the Floating Dock mooring, Other photographs confirm that the general area where the Floating Dock was usually anchored was in the approximate area of the winching shed of the present slipway.

Undated view of harbour showing position line from end of the Whalers Jetty to slightly east of Bridge Street. No te the Whalers Jetty was demolished and the extent demolished can be seen by comp arison with the modern situation in Figure Position line from Old Town Baths. Position lines taken from following three historical photographs.

Although the area has been previously dredged from the area includes the earlier jetty alignment and has low concentrations of 19 th and 20th century artefacts.

Garratt, et al. These were in shallow water ottles, a piece of slate, rocks, silt and shells. Below this layer a distinctive undisturbed, thick, tightly packed shell matrix mixed with clean white sand was encountered, and this was sounded down to 3.

Some of the shells were extremely large oyster shells causing dredge blockages. This may be related to the deeper layers encountered in the excavation that were dated to years BP.

This depth was the maximum working extent of the water dredge without enlarging the grid square due to the coning effect of trench walls in a sandy marine environment , and with no sign of any further layering or signs of cultural material other than the thick shell bed the excavation was discontinued.

Interestingly and somewhat surprisingly there were few artefacts in Grid 2, even though it was towards the earlier shore end of the Town Jetty. A photograph taken from the Residency Point in January looking across the shallow flats fronting Albany shows the shallow seabed prior to its reclamation.

The sea grass and shell layers encountered in both of the excavation grids were at the deeper end of the shallows as the seabed sloped into deeper water.

Archaeologists excavating test square. Seagrass matte. Modern artefaccts on the sea bed. The conservation survey undertaken in was comp rehensive and a range of data recording methods were used to assess both the seawater and seabed environment and to determine the condition of a selection of submerged materials both organic and inorganic.

The temperature, pH, redox potential, dissolved oxygen content and salinity of the local water column and the pH and redox potential of the sediment in the test excavation squares were measured.

The condition of the wooden jetty pile remains was also assessed. This report is an adjunct to the more comp rehensive conservation survey and briefly discusses the local underwater environment and the integrity of the submerged jetty piles. Measurements of pH were effected by a BDH GelPlas flat surface pH electrode connected to a Cyberscan pH meter sealed inside the custombuilt plexiglass waterproof housing. The water depth was measured with a digital dive comp uter.

The temperature, salinity and dissolved oxygen concentration of the seawater column was measured on-site at 0. The condition of the wooden jetty piles was assessed by the simple probe penetration test, where a stainless steel probe is physically pushed into the surface of the wood as far as possible and then the depth of penetration mm recorded.

The results are presented in Table 1. Temperature, salinity and dissolved oxygen content of the water column on the Albany Town Jetty site. Over the seven day site investigation period, the average water temperature was The average dissolved oxygen content salinity comp ensated at the seawater surface was 7.

These results indicate that the Albany Town Jetty site is a typical aerobic marine environment and are in general agreement with Atkins et al. There was no significant change in salinity with depth but the general decreasing trend of dissolved oxygen concentration with increasing water depth is typical for an open circulation ocean environment Figure However, the solubility of oxygen in 33 seawater increases with decreases in temperature and salinity.

In addition, the significant decreases in both the dissolved oxygen content and temperature measured at 2. The dissolved oxygen electrode is basically a Clarke electrode and as such requires the free movement of oxygen to the electrode surface to gain accurate readings. If the free flow of oxygen to the electrode surface is suppressed, such as when the electrode is in intimate contact with sediment, then the amount of dissolved oxygen reaching the electrode surface will decrease and the readings will consequently decrease.

Hence, these two readings were removed prior to graphing the dissolved oxygen values versus water depth Figure Change in dissolved oxygen concentration with increasing water depth on the Albany Town Jetty site. It can be clearly seen from Figure 30 that when the dissolved oxygen contents are corrected for the temperature difference there is very little variability between the dissolved oxygen concentrations of the water column measured at different times and positions during the investigation period.

Changes in these physical parameters can affect the corrosion and degradation rates of inorganic and organic materials in the marine environment, however the Albany Town Jetty site was relatively stable with respect to these parameters.

The pH of different sedimentary layers in the excavation pits as a function of increasing sediment depth. The redox potential of different sedimentary layers in the excavation pits as a function of increasing sediment depth.

Ex c AvA t iO n pit 1 The sedimentary profile of pit 1 consisted of a thin surface layer of contemporary seagrass, sand, silt and shell overlying a layer of sand, silt and shell to a depth of 0. After this depth the sediment layer became more comp acted until a dead seagrass layer was reached at the base of the pit at a depth of 0.

No measurements were recorded in the sondage. The pH then decreased until it stabilised at approximately 7. The pH then decreased slightly again when the dead seagrass layer was reached at the base of the pit due to the anaerobic de comp osition of the plant matter by facultative and nearanaerobic bacteria producing weak acids and polysulphides.

The redox potential of the surface sediment was The voltage then decreased dramatically over the next 0. This is not unusual as sediments tend to become more reducing in nature as the dissolved oxygen content decreases with increasing sediment depth. Hence, the significant decrease in redox potential after 0. Ex c AvA t iO n pit 2 The sedimentary profile of pit 2, which was excavated closer to the jetty, differed markedly from pit 1.

The seabed surface consisted of sterile sand overlying a thick dead seagrass layer, which extended to a depth of 0. After this depth, comp acted shell and worm casts, including some very large oyster shells, mixed with clean white sand extended to the base of the pit 0. The average pH of the surface sediments 0. This sharp increase in pH would be due to significantly less quantities of deteriorating seagrass and increasing amounts of calcareous material present in this comp acted layer.

In addition, the pHs of the sediment measured in pit 2 were significantly lower than the those recorded in pit 1. This general increase in the acidity is simply due to the larger concentrations of degrading plant material in pit 2 as comp ared to the relatively sterile nature of the sedimentary layers in pit 1. The average redox potential of the seagrass layer in pit 2, which extended to a depth of 0. Increased biological deterioration of the detrital plant matter would deplete dissolved oxygen concentrations in this layer, thereby producing a more reducing environment in this relatively shallow depth range.

Below this depth, where the comp acted shell and sand layer was observed, the voltage increased quite rapidly to a maximum potential of The white appearance of the sand in this layer also supported a more oxidizing microenvironment as sediments in more reducing environments tend to become grey in colour.

This can be explained by the absence of large quantities of organic matter in this sedimentary layer. Microbial activity decreases significantly with a decrease in the quantity of organic matter present in a sediment and therefore less dissolved oxygen is utilised in metabolic processes and a concomitant increase in redox potential ensues. In addition, the results obtained from the chemical measurements of the sedimentary layers in excavation pits 1 and 2 are in general agreement with the data acquired from the N-S transect excavation pit 1 and the mail steamer jetty test pit 2 , respectively Garratt et al.

In brief, the results indicate that there are significantly greater quantities of detrital plant matter present in the sediments closer to the jetty. Therefore, microbial and chemical activity and hence, the rate of degradation of organic and inorganic materials, would be greater in sediment near the jetty than in the more sterile sediment east of the jetty. Conservator recording data in test pit. This recent degradation assessment was conducted by a simple probe penetration test, which can be used to qualitatively determine the extent of wood deterioration.

The results of the probe penetration test and the diameter measurements of the jetty piles on the Albany Town Jetty piles are presented in Table 3. The results of these probe tests are comp arable to the results obtained during the survey Garratt et al. Ar t E fAc t mAt E r i A l s The artefacts recovered from the two excavation pits comp rised of two modern beer bottles, a fragment of potentially older green glass and small pieces of wood that could possibly be small fragments or off-cuts from jetty construction work.

In conservation terms the condition of all of the glass was very good. The waterlogged wood was not affected by marine borers and appeared to retain its original form and dimensions. The well-preserved condition of the wood supports the original conclusions drawn and consequent predictions made about the preservation of organic materials that are likely to be found in the sediment environment surrounding the Albany Town Jetty and potential examples that may be found during excavations of the development site.

S, Rev. Bulletin of the Australasian Institute for Maritime Archaeology, 7— Special Publication No. More documents Similar magazines Info. Survey positions of histo Page 10 and Figure 7. An historic pil Page 12 and Figure 9. Plan of the track of the Page 14 and Figure Side scan trace of end o Page 20 and Figure Trace with the semi-tran Page 26 and Figure Position line from Old T Page 28 and ottles, a piece of slate, rocks, si Page 30 and Drawing of underwater excavation Gr Page 32 and Figure Share from cover.

Share from page:. Copy No.

 

No. Albany foreshore project. By J.N. Green (comp.),

 
Turn your PDF publications into a flip-book with our unique Google optimized Green, Michael McCarthy, Tracey Miller, Vicki Richards. Downloaded from replace.me on by guest. Jn Green Technical Drawing. Thank you very much for reading Jn Green Technical. in the course of guides you could enjoy now is technical drawing jn green below. Fox Valley Lutheran HS Fox Valley Lutheran High School COURSE WebRealistic.