Handy Tool Definitions

Concrete vs. Cement

Concrete and cement are (mostly) two different materials. Why mostly? Because concrete is made using cement. Though cement can (technically) be used on its own, concrete cannot be made without first making cement.

Classified as a ceramic, cement starts as a powder, a mixture of limestone and other minerals, which is heated and mixed with gypsum to form what we know of as cement. Still a powder in this form, once water is added and mixed the cement then hardens. 

Portland cement, probably the most well known and commonly used cement, is classified as a hydraulic cement. This essentially means that once water has been added the chemical reaction, called hydration, that hardens the cement is not dependent on how much water is added. Hydraulic cements can harden underwater and remain strong even in wet conditions. As a side note, Portland cement is not a brand name, but a particular type of cement.

On the other hand, concrete is composed of cement, aggregate, and water, and is thus classified as a composite. Composites are defined as consisting of a matrix or binder that has a reinforcement within it. In the case of concrete, the cement water mixture is the matrix in which the reinforcement, or aggregate exists. 

The aggregate is typically comprised of stones, rocks, and sand and its addition increases the durability of the concrete. The amount of the aggregate or the size of the aggregate added can also effect the water-to-cement ratio required to harden the material, strengthening the final product. The hardening process continues for years, meaning that concrete only gets stronger with age.

Though most concretes are lime-based, asphalt concrete uses asphalt as the cement material and polymer concretes also exist. Another common type of concrete is reinforced concrete, in which rebar, or reinforcing bars, are embedded within to add to the strength of the concrete.

Sources: ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 )

IMPOSSIBLE! Right? You may have heard “the interior angles of a triangle always add up to 180 degrees”. This is not always true. Check out the second image, it shows a triangle with 3 right angles for a total of 270 degrees! 

It is true in flat Euclidean geometry (the geometry you probably learned in school) however. But there are so many other geometries out there! You may be thinking, are other geometries real though? A mathematician would argue they are just as real as the typical flat geometry you know and love (or hate). These alternative geometries can be practically useful too!

The images above show triangles in spherical geometry. Those aren’t triangles though! Oh but they are! A triangle is just a polygon enclosed by three lines. Looks like it fits the criteria. Wait but those aren’t lines, they are curved! Ah yes. I argue that these are, for all intents and purposes, just as good as lines. We need to ask: What is a line? A line is so basic to us we may not know how to describe it. I offer this definition: A line is the shortest path between 2 points. The 3 curves that make the triangle above are in fact the shortest paths from one vertex to the other on the surface of the sphere (they just so happen to be on circumferences of the sphere, which are often referred to as great circles). So it may be more useful to think of lines, in general, as length minimizing curves. In conclusion, we would consider the shape above to be a triangle as it is enclosed by 3 length minimizing curves on a surface.

Spherical geometry can be very useful; think about the Earth. To reduce travel time, airplanes would want to travel along great circles as they are the shortest paths from one place to another. Additionally, this type of thinking (rethinking straight lines as length minimizing curves) is central to Albert Einstein’s general theory of relativity.

read more at http://staffrm.io/@missnorledge/35H6cS1T52

In mathematics there is a concept known as ‘Conformal Mapping’ which allows you convert a given shape to a completely different one by making a transformation.

In the joukowski transform you take all the points on a circle and apply the following transform:

And the resulting transformed points resemble an aerofoil shape. Pretty cool huh ?

** Conformal mappings are a really cool topic in complex analysis but also equally extensive. If you want to know more about them click here

Alloys: Wood’s Metal

Also known as Lipowtiz’s alloy as well as the commercial names of Cerrobend, Bendalloy, Pewtalloy, and MCP 158 among others, Wood’s metal is a bismuth alloy consisting of 50% bismuth, 26.67% lead, 13.33% tin, and 10% cadmium by weight. Named for the man who invented it, a Barnabas Wood, Wood’s metal was discovered/created by him in 1860.

Wood’s metal is both a eutectic and a fusible alloy, with a low melting temperature of approximately 70 °C (158 °F). While none of its individual components have a melting temperature of less than 200 °C, a eutectic alloy can be considered as a pure (homogeneous) substance and always has a sharp melting point. If the elements in a eutectic compound or alloy are not as tightly bound as they would be in the pure elements, this leads to a lower melting point. (Eutectic substances can have higher melting points, if its components bind tightly to themselves.)

Useful as a low-temperature solder or casting metal, Wood’s metal is also used as valves in fire sprinkler systems. Thanks to its low melting temperature, Wood’s metal melts in the case of a fire and thanks to the bismuth it is made from, the alloy also shrinks when it melts (bismuth, like water ice, is one of the few substances to do so) which is the key to setting off the sprinkler system. Wood’s metal is also often used as a filler when bending thin walled metal tubes: the filler prevents the tube from collapsing, then can be easily removed by heating and melting the Wood’s metal. Other applications include treating antiques, as a heat transfer medium in hot baths, and in making custom shaped apertures and blocks for medical radiation treatment.

With the addition of both lead and cadmium, however, Wood’s metal is considered to be a toxic alloy. Contact with bare skin is thought to be harmful, especially once the alloy has melted, and vapors from cadmium containing alloys are also quite dangerous and can result in cadmium poisoning. A non-toxic alternative to Wood’s metal is Field’s metal, composed of bismuth, tin, and indium.

Sources: ( 1 - image 4 ) ( 2 - image 2 ) ( 3 ) ( 4 )

Image sources: ( 1 ) ( 3 )

Hackaday Useful Tools Links

So I am an avid reader of Hackaday for a long time now and they have been putting out a lot of great introductions to tools and processes to get makers up to speed on the resources that are available.  This is just a splattering of links that I have found lately that you guys might be interested in.

DC Motors

Lessons in Small Scale Manufacturing

Grinding Gears: Figuring out gear ratios

Tools of the trade: Injection Molding

Are todays engineers worse?

How to nail a technical presentation

Tools of the trade: Vacuum Forming

The Art and Science of Bending Sheetmetal

A how-to of designing, fab, and assembly with structural framing systems (t slot)

Machine learning foundations

A machine shop in a box

How to: Cold resin casting

Join the GUI generation: Qtcreator

Do you guys have any other great resources that you’d like to share and/or are you enjoying this type of content?

PERIODIC SPONGE SURFACES AND UNIFORM SPONGE POLYHEDRA IN NATURE AND IN THE REALM OF THE THEORETICALLY IMAGINABLE

By Michael Burt- Prof emeritus, Technion, I.I.T. Haifa Israel

The diversity of shapes and forms which meets the eye is overwhelming. They shape our environment: physical, mental, intellectual. Theirs is a dynamic milieu; time induced transformation, flowing with the change of light, with the relative movement to the eye, with physical and biological transformation and the evolutionary development of the perceiving mind. “Our study of natural form “the essence of morphology”, is part of that wider science of form which deals with the forms assumed by nature under all aspects and conditions, and in a still wider sense, with forms which are theoretically imaginable…..(On Growth and Form – D'Arcy Thompson), “Theoretically” to imply that we are dealing with causal- rational forms. “It is the business of logic to invent purely artificial structures of elements and relations. Sometimes one of these structures is close enough to a real situation to be allowed to represent it. And then, because the logic is so tightly drawn, we gain insight into the reality which was previously withheld from us” (C. Alexander). A particular interest should be focused on those structures which are shaped like solids or containers, with continuous two-manifold enveloping surfaces, enclosing a volume of space and thus subdividing the entire space into two complementary sub-spaces, sometimes referred to as interior and exterior, although telling which is which, is a relativistic notion. On each of these envelopes, topologically speaking, an infinite number of different maps composed of polygonal regions (faces), which are bounded by sets of edge segments and vertices, could be drawn, to represent what we call polyhedra, or polyhedral envelopes. We come to know them by various names and notations, evolving through many historical cultures up to our present times; each representing an individual figure-polyhedron, or a family, a group, a class or a domain; convex-finite, Platonic and Archimedean polyhedra; pyramids, prisms; anti-prisms; star polyhedra; deltahedra; zonohedra; saddle polyhedra, dihedral, polydigonal, toroidal, sponge like, finite and infinite polyhedra; regular, uniform, quasi-regular, and so forth; all inscribable in our 3-dimensional space. It is these structures and their extended derivatives which shape our physical-natural or artificial man-conceived environment and provide for our mental pictures of its architecture. The number of forms which had acquired a name or a specific notation through the ages is amounting to infinity, although the number of those which comprise our day to day formal vocabulary and design imagery is extremely (and regretfully) limited by comparison, even amongst designers and architects, whose profession, by definition, compels them to manipulate and articulate forms and space. Here it is right to observe that name-giving is part of the creative and generative process. The number of polyhedral forms which did not receive, as yet a proper name or a notation is also infinite. Infinite is also the number of potentially existing and possible imaginary periodic forms, not envisaged yet. Conspicuous are those relating to sponge-like labyrinthian, polyhedral, space dividing surfaces, which until quite recently were not even considered as a research topic. The interest in these forms has been prompted by our growing awareness of their abundance in nature and their importance, not only in describing micro and macro-physical and biological phenomena, but also in coping with morphological complexity and nature of our built environment and its emerging new architecture and the order and formal character of our living spaces, on either the building or the urban scale. Nature is saturated with sponge structures on every possible scale of physical-biological reality. The term was first adopted in biology: “Sponge: any member of the phylum Porifera, sessile aquatic animals, with single cavity in the body, with numerous pores. The fibrous skeleton of such an animal, remarkable for its power of sucking up water”. (Wordsworth dictionary). the entire study here

© Michael Burt- Prof emeritus, Technion, I.I.T. Haifa Israel

Dude, bullets are literally made to shatter on impact. It's to prevent over-penetration. Bullets frequently shatter if they hit human bone inside a body, for example. So congrats, a katana is as good at stopping bullets as a human bone. Or a regular butter knife. Or even a regular piece of old steel. Like the ones used in a target range. Ever wonder why the steel plates at target ranges don't have holes in them even tho rifle caliber bullets hit them? It's cause the bullet shatters on impact.

To be very clear, the intention of the post was never to say that Katana is the ultimate sword. It was merely to enlighten the possibility of the bullet getting shattered by a sword/Knife.

Yes, bullets do shatter on impact.

But I am not so sure about what you say about the human bone though.

I believe it really depends on that kinetic energy of the bullet, the bullet size and the place of impact of the bullet on the body.

And even with the tissues surrounding the bone, there have been many instances where the Femur ( thigh bone ) fractured on impact.

If anyone reading this has a background in the field, would highly appreciate to hear your stance on this.

Thanks for asking anon ! :D

10 Secret Trig Functions Your Math Teachers Never Taught You

On Monday, the Onion reported that the “Nation’s math teachers introduce 27 new trig functions”. It’s a funny read. The gamsin, negtan, and cosvnx from the Onion article are fictional, but the piece has a kernel of truth: there are 10 secret trig functions you’ve never heard of, and they have delightful names like ‘haversine’ and ‘exsecant’.

Science Fact Friday: Bird lungs! Just like every other part of a bird, they’re weird.

This gif shows the path of a single breath, but the circuit holds 2 breaths at a time. So when the bird inhales, the just-inhaled breath goes through Inhalation 1 while the previous breath goes through Inhalation 2. Rinse, repeat. Thus, the lungs are constantly receiving oxygen - in mammals, our oxygen content dips slightly between inhalations because there’s no fresh air coming in. We also don’t empty 100% of our lung volume so some air is “stale” even during an inhalation.

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10 “Spinoffs of Tomorrow” You Can License for Your Business

The job of the our Technology Transfer Program is pretty straight-forward – bring NASA technology down to Earth. But, what does that actually mean? We’re glad you asked! We transfer the cool inventions NASA scientists develop for missions and license them to American businesses and entrepreneurs. And that is where the magic happens: those business-savvy licensees then create goods and products using our NASA tech. Once it hits the market, it becomes a “NASA Spinoff.”

If you’re imagining that sounds like a nightmare of paperwork and bureaucracy, think again. Our new automated “ATLAS” system helps you license your tech in no time — online and without any confusing forms or jargon.

So, sit back and browse this list of NASA tech ripe for the picking (well, licensing.) When you find something you like, follow the links below to apply for a license today! You can also browse the rest of our patent portfolio - full of hundreds of available technologies – by visiting technology.nasa.gov.

1. Soil Remediation with Plant-Fungal Combinations

Ahh, fungus. It’s fun to say and fun to eat—if you are a mushroom fan. But, did you know it can play a crucial role in helping trees grow in contaminated soil? Scientists at our Ames Research Center discovered that a special type of the fungus among us called “Ectomycorrhizal” (or EM for short) can help enhance the growth of trees in areas that have been damaged, such as those from oil spills.

2. Preliminary Research Aerodynamic Design to Lower Drag

When it comes to aircraft, drag can be, well…a drag. Luckily, innovators at our Armstrong Flight Research Center are experimenting with a new wing design that removes adverse yaw (or unwanted twisting) and dramatically increases aircraft efficiency by reducing drag. Known as the “Preliminary Research Aerodynamic Design to Lower Drag (PRANDTL-D)” wing, this design addresses integrated bending moments and lift to achieve drag reduction.

3. Advancements in Nanomaterials

What do aircraft, batteries, and furniture have in common? They can ALL be improved with our nanomaterials.  Nanomaterials are very tiny materials that often have unique optical, electrical and mechanical properties. Innovators at NASA’s Glenn Research Center have developed a suite of materials and methods to optimize the performance of nanomaterials by making them tougher and easier to process. This useful stuff can also help electronics, fuel cells and textiles.

4. Green Precision Cleaning

Industrial cleaning is hard work. It can also be expensive when you have to bring in chemicals to get things squeaky. Enter “Green Precision Cleaning,” which uses the nitrogen bubbles in water instead. The bubbles act as a scrubbing agent to clean equipment. Goddard Space Flight Center scientists developed this system for cleaning tubing and piping that significantly reduces cost and carbon consumption. Deionized water (or water that has been treated to remove most of its mineral ions) takes the place of costlier isopropyl alcohol (IPA) and also leaves no waste, which cuts out the pricey process of disposal. The cleaning system quickly and precisely removes all foreign matter from tubing and piping.

5. Self-Contained Device to Isolate Biological Samples

When it comes to working in space, smaller is always better. Innovators at our Johnson Space Center have developed a self-contained device for isolating microscopic materials like DNA, RNA, proteins, and cells without using pipettes or centrifuges. Think of this technology like a small briefcase full of what you need to isolate genetic material from organisms and microorganisms for analysis away from the lab. The device is also leak-proof, so users are protected from chemical hazards—which is good news for astronauts and Earth-bound scientists alike.

6. Portable, Rapid, Quiet Drill

When it comes to “bringing the boom,” NASA does it better than anyone. But sometimes, we know it’s better to keep the decibels low. That’s why innovators at NASA’s Jet Propulsion Laboratory have developed a new handheld drilling device, suitable for a variety of operations, that is portable, rapid and quiet. Noise from drilling operations often becomes problematic because of the location or time of operations. Nighttime drilling can be particularly bothersome and the use of hearing protection in the high-noise areas may be difficult in some instances due to space restrictions or local hazards. This drill also weighs less than five pounds – talk about portable power.  

7. Damage Detection System for Flat Surfaces

The ability to detect damage to surfaces can be crucial, especially on a sealed environment that sustains human life or critical equipment. Enter Kennedy Space Center’s damage detection system for flat composite surfaces. The system is made up of layered composite material, with some of those layers containing the detection system imbedded right in. Besides one day potentially keeping humans safe on Mars, this tech can also be used on aircrafts, military shelters, inflatable structures and more.

8. Sucrose-Treated Carbon Nanotube and Graphene Yarns and Sheets

We all know what a spoonful of sugar is capable of. But, who knew it could help make some materials stronger? Innovators at NASA’s Langley Research Center did! They use dehydrated sucrose to create yarns and woven sheets of carbon nanotubes and graphene.

The resulting materials are lightweight and strong. Sucrose is inexpensive and readily available, making the process cost-effective. Makes you look at the sweet substance a little differently, doesn’t it?

9. Ultrasonic Stir Welding

NASA scientists needed to find a way to friction weld that would be gentler on their welding equipment. Meet our next tech, ultrasonic stir welding.

NASA’s Marshall Space Flight Center engineers developed ultrasonic stir welding to join large pieces of very high-strength, high-melting-temperature metals such as titanium and Inconel. The addition of ultrasonic energy reduces damaging forces to the stir rod (or the piece of the unit that vibrates so fast, it joins the welding material together), extending its life. The technology also leaves behind a smoother, higher-quality weld.

10. A Field Deployable PiezoElectric Gravimeter (PEG)

It’s important to know that the fuel pumping into rockets has remained fully liquid or if a harmful chemical is leaking out of its container. But each of those things, and the many other places sensors are routinely used, tends to require a specially designed, one-use device.

That can result in time-consuming and costly cycles of design, test and build, since there is no real standardized sensor that can be adapted and used more widely.

To meet this need, the PiezoElectric Gravimeter (PEG) was developed to provide a sensing system and method that can serve as the foundation for a wide variety of sensing applications.

See anything your business could use? Did anything inspire you to start your own company? If so, head to our website at technology.nasa.gov to check them out.

When you’ve found what you need, click, “Apply Now!” Our licensing system, ATLAS, will guide you through the rest.

If the items on this round-up didn’t grab you, that’s ok, too. We have hundreds of other technologies available and ready to license on our website.

And if you want to learn more about the technologies already being used all around you, visit spinoff.nasa.gov.

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