Results for: “Technology & Engineering”
|Charles Platt||Maker Media, Inc||ePub|
To avoid misunderstandings regarding the purpose and method of this book, here is a quick guide regarding the way in which it has been conceived and organized.
As its title suggests, this is a reference book, not a tutorial. In other words, it does not begin with elementary concepts and build sequentially toward concepts that are more advanced.
You should be able to dip into the text at any point, locate the topic that interests you, learn what you need to know, and then put the book aside. If you choose to read it straight through from beginning to end, you will not find concepts being introduced in a sequential, cumulative manner.
My book Make:Electronics follows the tutorial approach. Its range, however, is more circumscribed than that of this encyclopedia, because a tutorial inevitably allocates a lot of space to step-by-step explanations and instructions.
This book is oriented toward practicality rather than theory. I am assuming that the reader mostly wants to know how to use electronic components, rather than why they work the way they do. Consequently I have not included any proofs of formulae, any definitions rooted in electrical theory, or any historical background. Units are defined only to the extent that is necessary to avoid confusion.See All Chapters
Assessment of Maize-based
Production Systems (CAPS) in Rainfed Uplands of Odisha,
Pravat Kumar Roul,1* Aliza Pradhan,2 Kshitendra
Narayan Mishra,1 Plabita Ray,1 Travis Idol,2 Satya
Narayan Dash,1 Catherine Chan2 and Chittaranjan Ray2
Orissa University of Agriculture and Technology, Bhubaneswar, India;
University of Hawai‛i at Maˉnoa, Honolulu, Hawaii, USA
Rainfed agroecosystems, the purported gray patches untouched by the Green
Revolution or most technological advances, occupy a prominent position in
Indian agriculture. However, since productivity of the country’s irrigated areas has almost reached a plateau, future growth in farm productivity will likely come from rainfed agroecosystems. The rainfed zones of India, with annual rainfall ranging from 500 to 1,500 mm, constitute 60% of the country’s net cultivated area. Calculations based on rainfall distribution pattern and soil type showed that even if the full irrigation potential of the country was realized, 50% of the net sown area would remain rainfed.See All Chapters
|Alan Beaulieu||O'Reilly Media||ePub|
Data is generally stored at the lowest level of granularity needed by any of a databases users; if Chuck in accounting needs to look at individual customer transactions, then there needs to be a table in the database that stores individual transactions. That doesnt mean, however, that all users must deal with the data as it is stored in the database. The focus of this chapter is on how data can be grouped and aggregated to allow users to interact with it at some higher level of granularity than what is stored in the database.
Sometimes you will want to find trends in your data that will require the database server to cook the data a bit before you can generate the results you are looking for. For example, lets say that you are in charge of operations at the bank, and you would like to find out how many accounts are being opened by each bank teller. You could issue a simple query to look at the raw data:See All Chapters
|Raye Ringholz||Utah State University Press||ePub|
IT WAS A TYPICAL FEBRUARY DAY in Salt Lake City. Grey. Cold. Intermittent blizzards raged over dirty corn snow speckled with dead leaves exposed by a false spring thaw. Duncan Holaday, sitting in his office in the two-story wooden building that used to be a World War 11 army barracks, couldn’t even see the city in the valley below. Showers of snowflakes blocked out the granite Mormon temple spires topped by the golden statue of Moroni blowing his trumpet. The Walker Bank, Utah’s sixteen-story “skyscraper,” was invisible. The Great Salt Lake, pewter-colored, disappeared into the whitened west.
The Public Health Service Occupational Health Field Station stood in the foothills of the snowclad Wasatch Mountains, on the east bench of the valley. It was a small island tucked away from the real world. The difficulty Duncan Holaday was having getting people to heed his warnings made him feel even more isolated.
He had been on the phone all morning. Calls to Blair Burwell of Climax Uranium Company, J.H. Hill of U.S. Vanadium, Howard Balsley, secretary of the Independent Vanadium and Uranium Producers Association, and Denny Viles of Vanadium Corporation of America. When his requests for meetings were met with polite acquiescence, he set up a series of appointments at various offices in Grand Junction, Moab, Cortez and Durango, Colorado, and Salt Lake City for mid-March. State and federal health and mining officials would join the discussions. Holaday hoped the meetings wouldn’t be a replay of old scenarios . . . his reports on radon counts in the mines and mills . . . his suggestions for ways the companies could reduce the radiation hazard through increased ventilation, use of respirators, and other safety practices . . . their show of concern and promises of change that resulted in little action.See All Chapters
Many extracts and individual allelochemicals from plant sources have given excellent results in laboratory conditions. In field situations, only a few are satisfactory alternatives to traditional pest management.
Chemical control usually involves broad- spectrum insecticides, and they have to be broad-spectrum by necessity, for they must sell in large enough amounts to accommodate financial development, research and marketing. The class of plant products is tested against one or a small group of insects attacking a specific crop. As a compound, if toxic, it could inhibit the feeding of one species, but for another it may be ineffective, or just an attractant or a growth inhibitor. Thus, replacement of a traditional chemical with a specific allelochemical will make pest management more expensive (Koul, 2008).
Over the past 20 years, domestic Chinese enterprises have invested considerable manpower and resources in developing botanical pesticides and they have achieved remarkable results. Compounds such as rotenone, martine, nicotine, toosendanin, veratridine, limonin, eucalyptol, and azadirachtin from the neem tree, have become registered products in China. Available statistics suggest that various plant-based pesticides are manufactured in 13 Chinese provinces and, overall, 43,000 varieties of plants are availableSee All Chapters
|Maddox, Sarah||XML Press||ePub|
A wiki adds an edit button to a web page. At its simplest, a wiki is a piece of server-based software that makes it possible for people to edit a web page and save their changes to the server. When other people request the page, the wiki serves them the updated content.
Lets look at it from the users point of view. This is the first time we see Ganache, our intrepid hero, in action. Ganache is a wiki whisperer. She knows wikis inside out and will lead you right up to that wiki so that you can whisper in its ear.
In this first scenario, Ganache is using a web browser to view a web page that is hosted on a wiki. The wiki has added that famous Edit button to the web page. Ganache spots an annoying typo on the page. She clicks the edit button. The page changes to edit mode and Ganache fixes the error. She clicks Save. The wiki applies the changes on the server side, updating the wiki database, and reloads the page in view mode. Ganache now sees the updated version of the page. So does everyone else.See All Chapters
|Backstop Media||Maker Media, Inc||ePub|
By Sara Gorecki
At JSConf 2014, NodeBoats was kicked-off with a full-day workshop: robots + water = fun! By the end of the day, participants had their boats sailing across the hotel pool, controlled from their laptops. I was part of a team of four that helped guide attendees through the process of creating their own seaworthy robots. This chapter will show you how to make one, too, as shown in Figure 3-1.
One of the challenges of creating a boat is physically untethering your hardware from your computer. After all, you don’t want to have to bring your laptop into the pool with you, or have your boat limited by the length of your USB cable. To this end, we’ll use the Spark Core to control our boat. See “Spark WiFi Development Kit” for more on Spark Core.
As you can see in Figure 3-1, the sealable plastic container will be the hull of your boat, so make sure it’s watertight! You want your breadboard and battery holder to fit comfortably inside, side by side. The boat pictured was made out of a 8.5” × 5.5” × 2.5” plastic pencil case with a cover that snaps closed (we purchased ours at a craft store), but a disposable food container or a small storage bin would work just as well. Just make sure you’re willing to make a hole in whatever you decide to use.See All Chapters
|Tom Szaky||Berrett-Koehler Publishers||ePub|
© Vladimir Jotov/Shutterstock.com
When I was a child, I had a pet rabbit that lived in a large cage on our apartment balcony. Every day I would feed her the vegetable peelings from our kitchen; she would happily eat them, later pooping out whatever her body didn’t use as spherical, pearl-like droppings in one corner of her cage. She would spend the rest of her time hanging out, dreaming perhaps about nice boy rabbits, in another corner of the cage. I never once saw her venture near the “poop corner” unless she had some specific business to do. Come to think of it, if I were that rabbit, I probably wouldn’t either.
The desire to be as far away from one’s own waste as possible seems to be hardwired in us. Landfills constantly face NIMBY (“not in my backyard”) challenges when getting zoned, and property values are lower near sewage treatment facilities, landfills, and composting sites. People simply don’t like hanging out near waste. Perhaps that is one of the reasons why we invented the toilet. If you deconstruct what a toilet is, beyond being a nice ceramic seat, it’s a device whose purpose is to move our waste far away from us as fast as mechanically possible.See All Chapters
|Dr. Sangeeta Chaudhary||Laxmi Publications|
CRYSTAL DIODE RECTIFIERS
For reason associated with economics of generation and transmission, the electric power available is usually an a.c. supply. The supply voltage varies sinusoidally and has a frequency of 50 Hz. It is used for lighting, heating and electric motors. But, there are many applications (e.g., electronic circuits) where d.c. supply is needed. When such a d.c. supply is required, the main a.c. supply is rectified by using crystal diode. The following two rectifier circuits can be used:
(i) Half-wave rectifier
(ii) Full-wave rectifier.
(U.P. Tech. Sem. Exam., 2004–05)
In half-wave rectification, the rectifier conducts current only during the positive half-cycle of input a.c. supply. The negative half-cycles of a.c. supply are suppressed i.e., during negative half-cycles, no current is conducted and hence no voltage appears across the load. Therefore, current always flows in one direction (i.e., d.c.) through the load though after every half-cycle.See All Chapters
|Fuglie, K.O., Ball, V.E., Wang, S.L.||CABI|
Measurement of Canadian
Agricultural Productivity Growth*
Sean A. Cahill and Tabitha Rich
Agriculture and Agri-Food Canada, Ottawa
In any area of economic research, long time series are valuable because they give a much more complete picture of a trend than shorter series. A difference between the growth rate of one short time series and that of another might indicate a fundamental change or it might simply be due to random deviations from trend. Statistical tests and econometrics can help in determining the significance of the difference, but analysis with a longer time series around these points will always provide more convincing evidence. For productivity growth, where differences in average rates of growth between periods are closely scrutinized and labelled as gaps, slowdowns and so on, there is clear value in a time series that will span these periods and help determine whether or not fundamental changes have taken place.
Over the past 50 years, there have been three studies that together now offer more than 80 years of data on productivity growthSee All Chapters
|John Graham-Cumming||O'Reilly Media||ePub|
Zentralfriedhof, Vienna, Austria
48 8 58 N, 16 26 28 E
A Scientist Among the Composers
If you need an excuse to visit the beautiful Austrian capital, then use the Zentralfriedhof (Central Cemetery) as your reason. Although the cemetery may not be one of the most famous attractions in Austria, it is the final resting place of many celebrated Austrians (and others), including Beethoven, Brahms, Schubert, four Strausses, and a host of other artists and politicians. But the grave thats waiting for scientific visitors is the one with a fundamental equation of thermodynamics written upon it.
That grave belongs to Ludwig Boltzmann, the Austrian physicist who created statistical mechanics (which helps to explain how the fundamental properties of atoms, such as mass or charge, determine the properties of matter) and showed that the laws of mechanics at an atomic level could explain the second law of thermodynamics (roughly that heat cannot flow from a cool body to a hotter body) via Boltzmanns Equation (see Equation 2-1).See All Chapters
|Edited by Arvind Kumar, S.S. Banga, F.D. Meena and P.R. Kumar||CABI|
P.R. Verma,1 G.S. Saharan2 and P.D. Meena3*
Agriculture & Agri-Food Canada, Saskatoon, Saskatchewan, Canada;
Department of Plant Pathology, CCS Haryana Agricultural University,
Hisar, India; 3ICAR-Directorate of Rapeseed-Mustard Research,
Albugo candida (Pers. ex. Lev.) Kuntze. (A. cruciferarum
S.F. Gray) is an oomycete belonging to the family Albuginaceae (Albugonales, Peronosporomycetes). It is an obligate parasite responsible for the white rust disease of many cruciferous crops. It causes both local and general infection (Saharan and Verma, 1992). Local infection produces white to cream pustules on the lower (abaxial) surface of leaves and stems or pods, while general, or flower bud infection (Verma and Petrie, 1980) causes extensive distortion, hypertrophy, hyperplasia and sterility of inflorescences generally called
‘staghead’. The staghead phase accounts for most of the yield losses attributed to this disease. The combined infection of leaf and inflorescence caused extensive yield losses up to 30–60% in severely affected fields in turnip rape (Brassica rapa L.) (Petrie, 1973; Harper and Pittman, 1974; Petrie and Vanterpool,See All Chapters
|Banwart, S.A., Noellemeyer, E., Milne, E.||CABI|
Soil Carbon Dynamics and
David Powlson*, Zucong Cai and Philippe Lemanceau
The quantity of organic carbon in soil and the quantity and type of organic inputs have profound impacts on the dynamics of nutrients. Soil organic matter itself represents a large reservoir of nutrients that are released gradually through the action of soil fauna and microorganisms: this is especially important for the supply of N, P and S to plants, whether agricultural crops or natural vegetation. Organic matter also modifies the behaviour and availability of nutrients through a range of mechanisms including increasing the cation exchange capacity of soil, thus leading to greater retention of positively charged nutrient ions such as Ca, Mg, K, Fe, Zn and many micronutrients. Carboxyl groups in organic matter, and in root exudates or microbial metabolites, form complexes with various metal ions, usually increasing their availability to plants. In some cases, the formation of stable complexes has a detoxifying effect, for example by making Al and Cu less available to plants or microorganisms. Organic matter influences soil physical conditions greatly, especially through the formation or stabilization of aggregates and pores; this indirectly influences the availability of water and dissolved nutrients to plant roots. Organic matter and organic inputs are the source of energy for heterotrophic soil organisms, variations in organic carbon content and composition, impacting biome size, diversity and activities. These complex interactions between organic carbon and the soil biome require additional research to be fully understood. The implications for nutrient dynamics differ between nutrient-rich situations such as agricultural topsoils and nutrient-poor environments such as subsoils or boreal forests. In agricultural soils, excessive inputs of organic matter in manures can lead to pollution problems associated with losses of N and P.See All Chapters
|Sandy Antunes||Maker Media, Inc||ePub|
Picosatellites, like any Low Earth Orbit satellite (LEO), are going up to, well, LEO. Space weatherradiation and energetic particles emitted from an active Suncan damage satellites. This region of space is partially protected from the worst effects of space weather by the Earths ionosphere, but it is an active and threatening place.
If space wasnt active, there wouldnt be any point in sending up my own Project Calliope to measure it. However, wed prefer to keep the physical damage to the electronics to a minimum. The primary source of damage due to solar activity is due to highly energetic electrons, protons, and ions emitted by the Sun (see Figure3-1).
Figure3-1.Aurora caused by solar activity charging the Earths ionosphere, as viewed from space. Image courtesy of NASA.
The particle and radiation environment is not static. Besides time variation due to solar activity, the shape of the Earths magnetic field also can lead to dips in the field that cause a higher hazard in certain geographic areas. The most known dips are where the field lines converge at the Earths north and south poles. These are responsible for the aurora. There is also a dip near Brazil, called the South Atlantic Anomaly (SAA) (Figure3-2) that LEO satellites can pass through during one or more orbits each day. Satellites with sensitive detectors often decide to either shut down or cease collecting data during the SAA passage, as the increased background can make the data too noisy to use (as well as risking damage to the satellite electronics).See All Chapters
|Renee DiResta||O'Reilly Media||ePub|
So far, we’ve covered how to get from vision to physical product and how to raise the funding necessary to seed your company. Now it’s time to talk about building the business: business models, pricing, marketing channels, distribution, logistics, and more. Taking a product to market is a complex process. This chapter will focus on the most common issues you’ll enounter on the road to getting your product into the hands of customers. Some questions that we’ll touch on include:
Many first-time hardware founders think their business model is obvious—they’re going to sell a device! However, a number of other options might be more suitable in terms of both revenue and customer loyalty.
Regardless of the business model you choose, you’ll have to determine how much to ask your customers to pay for your device, or device experience.
Here we’ll discuss the costs and the pros and cons of various distribution options. This will also be where we discuss raising awareness, advertising, and marketing, because strategies often vary depending on the distribution channel.See All Chapters