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News: Welcome to the Australianelectronicgoldprospectingforum founded in July 2010, an add free totally independent forum with over 70 boards and paid for and managed by the Admin.Total forum Topics: 8,946   Total forum Posts:43,065 Members:719 Total page views:11,023,726 Admin and  forum and domain name owner :marjen at optusnet.com.au. Guests can only see a limited number of boards at present and cannot see any hot links. Guest cannot post and never will be permitted too!Registration of new members must be approved by admin.Anyone known to have any past or present association with Codan/ML or acting on their behalf as a proxy or intermediary  will not have their registration approved. All  original Photos and posts and  original materials displayed on this site are COPYRIGHTED and remain the property of the poster and the  Austalian electronicgoldprospectingforum.com. All messages on this forum express the personal views of the author and should not be interpreted as necessarily being in accord with those of the forum owner and neither the owner of this forum and its domain name nor SMF or the forum software developers or the forum host shall be held responsible for the content of any message. Admin reserves the right to remove any offensive or objectionable posts. No defamatory material or politics/religion or issues of race will be permitted.
Proven forum hackers  and those permitting defamatory content on their "forum" will never  be permitted to join or rejoin the forum.
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HOT Topics!
The need for big deep gold detectors. Over 14,000 views and 37 pages!!! This forum has brought you the QED("the best value for money Pi on the market"!),now to bring you  better coils!I do NOT receive ANY direct or indirect pecuniary or ANY other benefits from the sale or promotion of the QED.Any such assertions are untrue and defamatory!!
link-http://australianelectronicgoldprospectingforum.com/detector-coils/the-need-for-big-deep-gold-detectors/msg44569/?topicseen#msg44569
Doug is right on  climate change! "HappySAD7000user" and "Inhere"  and "Arizona"and the  village idiot 1halfgram4three are wrong! They are  scientifically illiterate, climate denier easy beats!!!! They are terrified of the truth and too spineless to come here and debate the issue!!!
The changing climate is NOT due to natural variation!
The  enormous body of diverse evidence, the physics and the overwhelming majority of climate scientists publishing in  recognized peer reviewed scientific journals agree that the earth is warming due predominately to  rising atmospheric  levels of anthropogenic C02!

australian electronic gold prospecting forum.com  |  Recent Posts
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 61 
 on: Thursday April 5 2018 21:06:13 AEST PM 
Started by Aziz - Last post by Aziz
  
Why is the sound card LCR meter is by far more accurate than the 220 bucks digital LCR meter?  shocked
doug smile

Hi Doug,

it is quite simple:
1. Better calibration & measurement software
2. Higher measurement resolution (24 Bit ADC)
3. Higher noise immunity (more averaging between measurements)
4. More precision reference resistors used
5. Optimal measurement range selection

I don't even need Kelvin clips & circuit to outperform an expensive digital LCR meter.

My actual accuracy is 0.1%. My next goal is to achive 0.032% accuracy.
 smile
Cheers,
Aziz

 62 
 on: Thursday April 5 2018 20:36:27 AEST PM 
Started by Aziz - Last post by Doug
  
Hi all,

here is a big surprise! 

My 5 bucks sound card LCR meter is by far more accurate than the 220 bucks digital LCR meter.
What a waste of money! 

I'll upgrade my sound card LCR meter circuit to be able to calibrate into 0.03 % accuracy.

Unfortunately the measurement accuracy is required to check some coil shielding capacitance calculations and the coil software.
Cheers,
Aziz

Why is the sound card LCR meter is by far more accurate than the 220 bucks digital LCR meter?  shocked
doug smile

 63 
 on: Thursday April 5 2018 20:18:31 AEST PM 
Started by Aziz - Last post by Aziz
Hi all,

here is a big surprise! 

My 5 bucks sound card LCR meter is by far more accurate than the 220 bucks digital LCR meter.
What a waste of money! 

I'll upgrade my sound card LCR meter circuit to be able to calibrate into 0.03 % accuracy.

Unfortunately the measurement accuracy is required to check some coil shielding capacitance calculations and the coil software.
Cheers,
Aziz

 64 
 on: Thursday April 5 2018 16:17:08 AEST PM 
Started by Doug - Last post by Doug
"OLD  MATE" on finders should  get his facts correct and then he won't make himself look like a fool.At the time i made the above post 1/2 wits forum was down.
doug smile

 65 
 on: Tuesday April 3 2018 17:29:42 AEST PM 
Started by Aziz - Last post by Aziz
Hi all,

it seems, that the direct parasitic capacitance Cp measurement using an impedance meter isn't easy and requires a very very accurate measurement. The bandwidth of my impedance meter (sound card LCR meter) is limitted up to the nyquist frequency of 48 kHz (96 kHz sampling rate) and make measurements difficult. And the impedance change at high frequency (up to 48 kHz) is quite low to get accurate Cp readings.

The Monte Carlo algorithm worked very nice. But the real measurements screwed the accuracy. Overall it was a nice practice to calculate with complex numbers. I will try it again, when I have increased the accuracy of my sound card LCR meter further.

Be aware of when measuring a coil at high test frequency will give you wrong readings (higher inductance L and high coil series resistance Rs), when the coil Cp is high. But there is no problem at low test frequencies up to 1 kHz however.

Cheers,
Aziz

 66 
 on: Tuesday April 3 2018 16:04:26 AEST PM 
Started by Doug - Last post by Doug
1/2 wits forum is down! Clap Hands Be good if it was permanent!Maybe the climate change shellacking  i have given him here was too much for him and Arizona!
doug smile

 67 
 on: Tuesday April 3 2018 14:19:02 AEST PM 
Started by Doug - Last post by Doug
Here are some excerpts from papers to debunk the rubbish posted  by the village idiot(and proven forum hacker!) and easy beat and  intellectual push over on another "forum"!
Similar estimates of temperature impacts on global wheat yield by three independent methods
Abstract
The potential impact of global temperature change on global crop yield has recently been assessed with different methods. Here we show that grid-based and point-based simulations and statistical regressions (from historic records), without deliberate adaptation or CO2 fertilization effects, produce similar estimates of temperature impact on wheat yields at global and national scales. With a 1?°C global temperature increase, global wheat yield is projected to decline between 4.1% and 6.4%. Projected relative temperature impacts from different methods were similar for major wheat-producing countries China, India, USA and France, but less so for Russia. Point-based and grid-based simulations, and to some extent the statistical regressions, were consistent in projecting that warmer regions are likely to suffer more yield loss with increasing temperature than cooler regions. By forming a multi-method ensemble, it was possible to quantify ‘method uncertainty’ in addition to model uncertainty. This significantly improves confidence in estimates of climate impacts on global food security.
  

Increasing influence of heat stress on French maize yields from the 1960s to the 2030s
Ed Hawkins?1, Thomas E. Fricker2, Andrew J. Challinor3, Christopher A. T. Ferro2,4,
Chun Kit Ho1, and Tom M. Osborne1
1NCAS-Climate, Department of Meteorology, University of Reading, Reading, UK
2College of Engineering, Mathematics and Physical Sciences, University of Exeter,
Exeter, UK
3Institute for Climate and Atmospheric Science, University of Leeds, Leeds, UK
4NCAS-Climate, University of Exeter, Exeter, UK
In press at Global Change Biology
October 15, 2012
Abstract
Improved crop yield forecasts could enable more effective adaptation to climate variability and change. Here we explore how to combine historical observations of crop yields and weather with climate model simulations to produce crop yield projections for decision relevant timescales. Firstly, the effects on historical crop yields of improved technology,precipitation and daily maximum temperatures are modelled empirically, accounting for a non-linear technology trend and interactions between temperature and precipitation, and applied specifically for a case study of maize in France. The relative importance of precipitation variability for maize yields in France has decreased significantly since the 1960s, likely due to increased irrigation. In addition, heat stress is found to be as important for yield as precipitation since around 2000. A significant reduction in maize yield is found for each day with a maximum temperature above 32?C, in broad agreement with previous estimates.
The recent increase in such hot days has likely contributed to the observed yield stagnation. Furthermore, a general method for producing near-term crop yield projections, based on climate model simulations, is developed and utilised. We use projections of future daily maximum temperatures to assess the likely change in yields due to variations in climate.Importantly, we calibrate the climate model projections using observed data to ensure both reliable temperature mean and daily variability characteristics, and demonstrate that these methods work using retrospective predictions. We conclude that, to offset the projected
increased daily maximum temperatures over France, improved technology will need to increase.base level yields by 12% to be confident about maintaining current levels of yield for the period 2016-2035; the current rate of yield technology increase is not sufficient to meet this target.
  

Insects Take A Bigger Bite Out Of Plants In A Higher Carbon Dioxide World

Evan H. DeLucia, Clare L. Casteel, Paul D. Nabity and Bridget F. O'Neill
PNAS February 12, 2008. 105 (6) 1781-1782; published ahead of print February 6, 2008.   
Carbon dioxide is a potent “greenhouse” gas. The dramatic increase in its concentration in the atmosphere as a result of human activities, beginning with accelerated fossil fuels combustion in the late 18th century, and perhaps even earlier, with modern agricultural expansion 8,000 years ago (1, 2), is driving a striking rise in global temperature (3). For the past 650,000 years, until relatively recently, the concentration of CO2 in the atmosphere was 280 ppm or less; however, the current concentration exceeds 380 ppm and, on its present trajectory, will surpass 550 ppm by 2050 (3). The accumulation of CO2 and other greenhouse gases in the atmosphere is forcing an elevation of global mean temperature; during the lifetime of child born today, the average temperature of the earth will increase by as much as ?6°C (3). Working in concert, elevated temperature and CO2 are redistributing plant and animal communities on the surface of the earth (4). Because of the direct effect of CO2 and temperature on global food supplies, the influence of these changes on plant physiology and ecology is being actively studied. How these elements of global change may alter the interactions between plants and the insects that feed on them is relatively unknown. By bringing to light secrets contained in the fossil record, Currano et al. (8), published in this issue of PNAS, found that the amount and diversity of insect damage to plants increased in association with an abrupt rise in atmospheric CO2 and global temperature that occurred >55 million years ago. If the past is indeed a window to the future, their findings suggest that increased insect herbivory will be one more unpleasant surprise arising from anthropogenic climate change.

Ask the Experts: Does Rising CO2 Benefit Plants?
Climate change’s negative effects on plants will likely outweigh any gains from elevated atmospheric carbon dioxide levels
“In addition to ignoring the long-term outlook, he says, many skeptics also fail to mention the potentially most harmful outcome of rising atmospheric CO2 on vegetation: climate change itself. Its negative consequences—such as drought and heat stress—would likely overwhelm any direct benefits that rising CO2 might offer plant life.
It’s not appropriate to look at the CO2 fertilization effect in isolation,” he says. “You can have positive and negative things going at once, and it’s the net balance that matters.” So although there is a basic truth to skeptics’ claim, he says, “what’s missing from that argument is that it’s not the whole picture.”
  

Plants release more carbon dioxide into atmosphere than expected

The study shows that as global temperatures increase, the amount of carbon dioxide released through plant respiration will increase significantly.
Professor Mark Tjoelker at Western Sydney University said changes to processes of photosynthesis and respiration in response to a warming climate would have profound implications in terms of the amount of carbon emissions from burning fossil fuels that plants can soak up.
"Increases in respiration in a warming climate could portend a declining capacity of vegetation to absorb carbon emissions," he said.
    
doug smile

 68 
 on: Monday April 2 2018 10:29:49 AEST AM 
Started by Doug - Last post by gef12
mongrels  GRR

 69 
 on: Sunday April 1 2018 16:10:42 AEST PM 
Started by Doug - Last post by Doug
  
What brand of detectors are stocked in Maldon shop?

  
doug smile

 70 
 on: Sunday April 1 2018 16:04:03 AEST PM 
Started by Doug - Last post by WM6
What brand of detectors are stocked in Maldon shop?

Pages: 1 2 3 4 5 6 [7] 8 9 10
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