Notes by Akshat Jiwan Sharma

The US policy makers are facing some tough choices as there's now an increased competition for talent from places like Europe,Australia,canada and even from asian nations like south korea , singapore ,saudi arabia ,UAE etc.  While I'm all for protecting domestic jobs there's the danger that USA may face significant competition in the coming decades from the nations that are eager to hire talented immigrants to build their industry.  The solution I think is to take lead in key industries to continue the growth. US did well initially with electric vehicles but it lost advantage. It has a lot going for it in AI and Google's quantum supremacy is promising for US deep tech. In semiconductors the chips and science act did well to promote local industries.  US still has one of the largest fiber optic cable manufacturers. It's telecom industry is doing reasonably well. Boeing  suffered some setbacks but other aviation components manufacturers like GE  are doing well. Th...

ABSTRACT A claim was made in the paper titled “Do electrons really flow as a beam in cathode ray tubes? ” where we asserted that electrons remain near the cathode surface during the operation of CRT. Here we do force calculations on electrons by estimating the debye length of electrons emitted after thermionic emission and show that under given applied voltages if electrons are placed at debye length they are sufficiently far away from the cathode surface to be accelerated towards it.  Debye length, while typically used to measure charge screening distance in plasmas and electrolytes, can also be used to estimate the distance of emitted electrons from the cathode surface.  In the same way debye length is used to calculate the thickness of an electrical double layer in which the surface charge and charge on inner helmholtz plane are immobile & the charges on outer helmholtz plane are mobile we can model emitted electrons as mobile charges & image charges distribute...

I only did an online course on Materials science not a full 4 year graduation programme so I may not be the best person to answer this question.  But I'd suggest do some research on job prospects in your area before enrolling. MS is more of a generalist subject that draws a lot from other disciplines. As a graduate you'll definitely find opportunities but not necessarily in the field of your study.  You may need to specialise in some domain later on.  Discovering & working on new materials is a lot of fun but their adoption is really slow. Be prepared to spend a lot of time on research in a lab.  If you really have a passion for materials then go for it and figure out a path later.  Personally I love materials science. It feels more real to me than other science and engineering domains. I love learning about new materials,their properties & their applications. I think it's a good skill to have but may not be the best from the point of view of landing a j...

I’m by no means an expert on the industry but I have a few observations that I would like to share with you. I think the biggest problem being faced by the telecom industry is commoditization of their core service. The way things stand people can’t really tell the difference between the operators. The only thing that makes them choose one over the other is the price. It does not really help that most of the work done by the industry is in the background that people don’t really notice much. Coverage is very important for a network, but a normal consumer does not really care about how many miles of fiber optic cables have been laid down. Or for that matter how many new towers have been set up (unless it is for protesting against the harmful effects of radiation, at which point they become surprisingly observant) Another problem that I see is a lack of technological understanding. In the initial years, the telecom industry was the leader in technology and was directly responsible for man...

Telecommunications is an international industry and many of the companies have a global presence. Although I have no experience working in the sector I follow it closely as a technology enthusiast. Telecom companies, today, operate like land owners. A network provider only cares about the product they can supply to the end user. All of the other things that go into making the network functional are of little concern and can be handled by someone else. They are not directly involved in construction,operation or even management of the networks. In order to run their business most “efficiently” nearly all of the functions are outsourced. Although the logic behind this outsourcing is to reduce the prices as well as the risk it would involve to do everything in house, the effect is the opposite. In my opinion. Spectrum licensing is handled by the government. While I believe that licensing is important, auctions are hurting the industry. But on the flip side without auctions telecom companie...

  Any wireless device has antennas that serve as the communication endpoints. That is the antennas are responsible for transmitting and receiving data. When your phone is in the hotspot mode it acts as a base station. In other words it is in the transmission mode (Tx) for wifi. To be able to receive the signal at the time you're transmitting you need at least two wifi antennas. If your mobile has it you can do it. If it does not then you can't. One of the reasons I think phone and chip designers try to limit the number of antennas is that they consume quite a lot of power. You want to maximize the battery life and minimizing the number of operational antennas is one way to do it. As an OS android which is built on linux kernel has no limitation that prevents any device from transmitting at receiving at the same time. The limiting factor is the hardware.

  Although with fiber optic connectivity you should get better speed and data caps at the same price, let us assume, for the sake of the question, that you don't and try to see what benefits optical fiber can bring you. Fiber optic connectivity will maintain service level standards for decades. The technology is mature and so capable that we don't have machines that can process their highest speeds. Fiber optic cables once installed are not going to go anywhere. Advancements in modulation techniques can be applied on the same cable without replacing them. Unless people are careless with installations (like digging where they are installed) fiber optics are here to stay. Given that fiber optic technology is operational for decades once installed year on year the price of running such a network will decrease. Companies can pass on the savings to the consumers or bring more people online by investing the savings. Because the internet is highly reliant on network effects you'll...

  Wireless networking is one of those things that is easier to do in practice than it is to learn in theory. You will learn more by jumping in right ahead rather than poring through the books. But if you’re an absolute beginner you need to start somewhere. So I’ll give an overview of the practical aspects of wireless networks first and towards the end of my answer I’ll give suggestions from where you can learn the theory. All wireless networks have three basic components Antennas that send out wireless signals A hardware that provides input signal to the antennas which it sends out wirelessly An operating system that controls the hardware, which sends the input signals to antennas, which then sends it out wirelessly. Now if you look at something as basic as a wifi router you’ll note that it has Antennas (either external or on chip) A chip to which those antennas are connected An OS (that is accessible through the web admin panel) that controls the chip So as a start you should try ...

   My answer will be a bit roundabout so apologies in advance. It may seem off topic but it will provide background for the actual question. Also I'm not a material science expert and only have second hand knowledge of both ceramics and LCP. Signal strength is one of the most important qualities to consider when designing an antenna both transmitting and receiving. But it's not the only one. Other factors like Ease of construction, installation and maintenance Environment in which the antenna operates The function it has to perform are just as relevant. It is important to stress on the third point because of something called reciprocity principal of antennas It states that properties governing transmission and reception are the same for an antenna. If the antenna is a good transmitter for a particular situation, it is also a good receiver. If we look only at signal strength then nothing can beat parabolic antennas. They are so powerful that they can communicate with satellites...

  Abstract: It is generally well accepted that a beam of electrons flow from cathode to anode in a cathode ray tube. Taking pressure  data from a variety of sources from CRT manufacturers’  data sheets to engineering documents of large hadron colliders we show through calculations that there is enough residual gas in these devices to form a conducting path from anode to cathode due to plasma formation. When high voltages are applied at the anode the gas is ionized and becomes a plasma forming a ‘wire’ between the two electrodes that causes conduction of energy.  The objective of this brief note is to encourage scientists and engineers to re-investigate commonly accepted beliefs about vacuum tubes and develop new knowledge that can revitalize the field especially at a time when nano scaled vacuum channel transistors are being envisioned.  Most vacuum tubes have  operating pressures in the ultra high vacuum range. This is true for cathode ray tubes, vacuum tu...

Dispersed cellulose nanocrystals self-assemble into solid films while preserving their chiral nematic liquid crystalline phase. These dried films display a characteristic iridescence that is caused by underlying photonic structure of the film.  During the self assembly process a helical arrangement of nanocrystals form a pattern that repeats itself. This period of repetition is called a pitch. The pitch determines what wavelength of light is reflected off from it (in a very photonic crystal like manner).  Smaller pitches reflect shorter wavelengths of light. Longer pitches reflect larger wavelengths of light. In the visible spectrum the pitch needs to be comparable to the color of light its reflecting. This behaviour has been observed from blue to red light but in other photonic crystals IR reflection has been obtained. So no reason that something similar won't happen in nanocellulose if pitch length can be appropriately tailored(incidentally there have been reports of nanocel...

1.They can be used as energy sources for HVDC generators. Stirling engines can easily & very naturally power van-de-graf/wimshurst  type machines.  2. They can be used to generate high quality plasma either via electrostatic generators as described in the point above or indirectly by converting transmitted electrical power to plasma.  3. Stirling engines are better than any thermoelectric generator. Instead of relying upon material properties to convert heat to electricity it uses  heat to perform mechanical work. Efficiency close to 30% is available in most designs & better engines can push past 40 & reach 50%. No solar energy system or a thermoelectric generator can ever hope to achieve those numbers. This property is especially imp. When you consider stirling engines can continue to generate power at night if energy can be provided. It's way easier to store heat than it is to store electricity.  4. Mechanical energy produced could have industrial ...

So tungsten has a very high MP exceeding 3000°C. It's advocates use this high MP to promote tungsten as a material of choice for high temperature applications. But there is a problem. Tungsten exhibits this high MP behaviour only in an atmosphere where no oxygen in present. If oxygen is present it oxidizes rapidly after 500°C and loses its strength,cracks etc.  If we consider inert atmospheres, even carbon has a sublimation point of 3600°C and as long as its surface can be prevented from oxygen attack it's safe to use in high temperature environments.  If we consider oxidative atmospheres then like tungsten graphite can handle temperatures upto 500c. Some reports suggest even more upto 700c Once tungsten has melted it would be of no use as a structural material though it can still be used as a coolant for extremely high temperature applications.  But if we consider terrestrial applications with reasonably high temperatures that are attainable in common use then carbon is ...

We previously described a layered carbon glass material system that is different from c/sic , c/sio2 matrix composites in that it consists of a distinct C/C phase which is coated by an sio2 layer.  https://akshatjiwannotes.blogspot.com/2024/12/low-energy-fabrication-of-high-strength.html This material system presents a distinct advantage in a high temperature oxidative atmosphere as the C/C matrix is protected by the oxidation resistant glass shield. Such a material can supposedly be synthesized in an open oxidative atmosphere. In this short note we will answer some questions such as  What manufacturing technique will be used?  How can silica particles be sintered on the substrate? How can adhesion between sintered particles and carbon substrate be ensured? What, if any ,sintering aids will be used? What would be the mechanical properties of the composite so formed?  What level of heat treatment will be required? To make the composite only the minimum amount of heat ...

High temperature materials are required in various applications: in metallurgy, for making combustion chambers of internal combustion engines ,for the body of Stirling engines, for wall material of nuclear fusion reactors, for the body of Jet engines among a few.  For such applications we need materials that can retain their strengths at elevated temperatures and can survive in an oxidative environment  It is the second requirement which is more stringent. Although numerous metallic alloys have been synthesized that can sustain both high temperatures and oxygen attack they require complex processing steps  On the other hand ceramics are good at resisting both oxygen attacks and high temperatures and are relatively simpler to fabricate but are limited by massive amounts of energy required. For example c/sic composites will perform well in demanding high temperature oxidative environments but require vacuum to be manufactured. The acheson process for the formation of sic is...

OTPs are like tokens that help each user connect to a network in a secure manner. A wireless network can be used in a way that a single password is not shared with multiple users. Each individual has his own password/token to access the network. Usually token based authentication is performed with the help of a captive portal. The user is redirected to a web page to authenticate. Web based authentication can take place over https so that the data transmission is encrypted. This setup is different from the one that we use in our homes, for example, where a single password is shared with the members of the family. Thus it overcomes the limitation of the WPA2 encryption scheme making it secure. [1] As for the limited part there could be multiple reasons. But it is important to remember here that airports are generally not responsible for providing internet/wifi. Most likely they outsource it to some service provider who then works with the management team and at some point in time they co...

  I may not be the best person to give career advice. Usually, unless you are well off economically,you have very limited moves straight out of college. The easiest thing is to apply for a job. In wireless technology this would mean Either with an OEM [ mobile phone manufacturers, radio equipment providers,chip makers etc] Or at an ISP/Mobile network operator Or at tower companies This is a good start. But I've noticed many people and especially students take up job hunting as a full time exercise. It is not. Devote a fixed amount of time looking for the positions you want ,3-4 hours, but after that invest everything into personal projects. Here you have a lot of freedom. You can either spend that time acquiring new skills like learning about software that controls wireless network systems or build products that can be sold, for example base stations and antennas. In India there's a big push towards rural connectivity. Companies like C-DOT are always looking for part time suppo...

   Wifi calling is an example of what are known as generic access networks (GAN) [1]. GANs allow you to access the networks of cellular providers through an external IP network. It is important to keep in mind however that Wifi Calling in the traditional sense is still a cellular call. By that I mean you are calling a number. Authentication, call connection , call routing all works as it would if you called directly. “How does it work in sync with the cellular provider?” For that we need to look into something called the IP Multimedia Subsystem (IMS). [I’ll limit this discussion to 4G networks but note that GAN also works for 2G networks just that the handoff method is a bit different requiring a GANC (C here stands for controller referring to a specific hardware device that transforms and forwards the data traffic from WiFi to cellular network processor)] IMS is a system for delivering communication services over an IP network. Before 3G ,services were delivered using a circu...

  Those are antennas. Point to point type. These antennas are highly directive and can haul wireless signals over several kilometers in a very narrow beam. As antennas are enclosed in a protective gear it can be a bit difficult to know what kind of antenna it is. To guess the kind of antenna the drum like shape is look at it from behind. If it is tapered towards the end then it is probably a horn. If it is round both front and back then its parabolic. Also the “horn drum” is a lot smaller than parabolic drum. In Fact it looks more like a bulb than a drum. Both horn and parabola are aperture antennas. Horn uses the principles of waveguide to provide smooth impedance matching (in simple words transition for the signal in wire to the signal in free space aka air). Whereas a parabolic dish uses the principle of reflection to focus the signal and aggregate into a beam to transmit it to long distance.