#engineering
My boss is my Wife’s half husband who can take her at night.
01/12/2021
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One of the best months of the year is starting today! I’m currently very busy studying for my exam this weekend ^^
Day 63/?
25/11/2021
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Today could have been better :/ But I did do some fun activities
Day 58/?
Why is breath sometimes cold and sometimes warm? (”hoo vs. haa”)
Hold your hand about a half foot (15 cm) from your mouth and open your mouth wide and blow air like you are fogging up a mirror. (”haa”) Your breath should feel warm. Now purse your lips and blow out. (”hoo”) Your breath should now feel cold. If you bring your hand closer to your mouth by about a centimeter away and blow out through pursed lips then your breath should feel warm again.
Why is this?
The air from your exhale is generally warmer than the ambient air outside your mouth. When your lips are pursed then the air is moving at higher speeds than with your mouth open. At these higher speeds the air from the exhale drags along the cooler still air due to friction. The breath air thus is doing work on this cooler so it also looses energy resulting in lower temperature. So overall the added cooler air and decreased temperature makes your breath feel cooler.
At distances closer to your mouth the warm breath air has yet to lose enough energy or drag along any cooler air so the breath still feels warm. With your mouth open the air is slower and takes up a larger volume so the majority of the air that reaches your hand is warm.
Many of you may recognize this photo of the x-ray diffraction pattern of DNA found by Rosalind Franklin and her PhD student, Raymond Gosling. But, you may wonder how one could figure out from this image that DNA is structured as a double helix and even how x-ray crystallography works.
X-Ray Crystallography
X-ray crystallography is a method of determining the positions and arrangements of atoms in a crystal. Crystals are usually defined to be a highly ordered and repeating microscopic structure of a solid rather than the macroscopic crystals we know like quartz which actually tend to be “polycrystals” because at a microscopic level they do have the highly ordered structure required. Ice is also a polycrystal composed of many smaller ice crystals.
1.) X-ray beams are shot at the crystals
The x-rays interact with electrons of the atoms. This interaction or collision is typically modeled by Thomson scattering where the energy and thus frequency of the x-rays do not change after diffraction. This is similar to light going through a diffraction grating.
2.) Beam is diffracted
The x-rays are diffracted based on the crystal lattice structure of the substance. This is dependent on the characteristics of the bonds between atoms like the bond angles and bond lengths. Also the spacing between molecules also determines the diffraction.
3.) Diffraction pattern
The diffracted x-rays are light waves so they interfere both constructively and destructively. The resulting intensities of the x-rays are recorded on a screen behind the sample to create a diffraction pattern. The sample is rotated to take more data. After sufficient data is taken a model for the crystal structure for the sample can be developed. With a diffraction pattern an electron density map can be made which depicts the location and size of electron clouds in the substance.
Above is an example of an electron density map.
As someone who used to play the bass guitar, I can’t believe I didn’t know how a guitarpickup works. The basic idea is actually relatively simple but the complexity comes when engineering the sound we hear from Jimi Hendrix, Jimmy Page, and B.B. King.
The mechanism is centered around Faraday’s Law of Induction. The guitar pickup in its simplest form is a permanent magnet(s) wrapped in a coil of wire. A permanent magnet is made from a ferromagnetic material (like iron) which is a special type of material where the “magnetic domains” are aligned with an external applied magnetic field.
The role of the permanent magnet is to magnetize the guitar string because it is also a ferromagnetic material like nickel or steel. When you pluck the string it vibrates and results in an oscillating(changing)magnetic flux through the coil. Because of Faraday’s Law of Induction this induces a signal(changing voltage) and thus current which is read by the amp to reverse engineer it into sound. Check out thisappletfrom the National High Magnetic Field Laboratory for a visual.
Since the string’s movement determines the signal picked up, the pickups receive a strong signal when directly under a part of the string moving with a large amplitude and frequency. So when it is directly under a node(where the string doesn’t move) like in the above picture (for the 7th harmonic), one of the pickups gets a very weak or possibly no signal. So in a way the pickups act as filtersfor the different harmonics depending on their placements which is key to the sounds we hear in the music. So as you can see the exact engineering can become extremely complicated
Read more…National Mag Lab…Guitar World…more on harmonics here
By Mohit Goenka, Gnanavel Shanmugam, and Lance Welsh
At Yahoo Mail, we’re constantly striving to upgrade our product experience. We do this not only by adding new features based on our members’ feedback, but also by providing the best technical solutions to power the most engaging experiences. As such, we’ve recently introduced a number of novel and unique revisions to the way in which we use Redux that have resulted in significant stability and performance improvements. Developers may find our methods useful in achieving similar results in their apps.
Improvements to product metrics
Last year Yahoo Mail implemented a brand new architecture using Redux. Since then, we have transformed the overall architecture to reduce latencies in various operations, reduce JavaScript exceptions, and better synchronized states. As a result, the product is much faster and more stable.
Stability improvements:
- when checking for new emails – 20%
- when reading emails – 30%
- when sending emails – 20%
Performance improvements:
- 10% improvement in page load performance
- 40% improvement in frame rendering time
We have also reduced API calls by approximately 20%.
How we use Redux in Yahoo Mail
Redux architecture is reliant on one large store that represents the application state. In a Redux cycle, action creators dispatch actions to change the state of the store. React Components then respond to those state changes. We’ve made some modifications on top of this architecture that are atypical in the React-Redux community.
For instance, when fetching data over the network, the traditional methodology is to use Thunk middleware. Yahoo Mail fetches data over the network from our API. Thunks would create an unnecessary and undesirable dependency between the action creators and our API. If and when the API changes, the action creators must then also change. To keep these concerns separate we dispatch the action payload from the action creator to store them in the Redux state for later processing by “action syncers”. Action syncers use the payload information from the store to make requests to the API and process responses. In other words, the action syncers form an API layer by interacting with the store. An additional benefit to keeping the concerns separate is that the API layer can change as the backend changes, thereby preventing such changes from bubbling back up into the action creators and components. This also allowed us to optimize the API calls by batching, deduping, and processing the requests only when the network is available. We applied similar strategies for handling other side effects like route handling and instrumentation. Overall, action syncers helped us to reduce our API calls by ~20% and bring down API errors by 20-30%.
Another change to the normal Redux architecture was made to avoid unnecessary props. The React-Redux community has learned to avoid passing unnecessary props from high-level components through multiple layers down to lower-level components (prop drilling) for rendering. We have introduced action enhancers middleware to avoid passing additional unnecessary props that are purely used when dispatching actions. Action enhancers add data to the action payload so that data does not have to come from the component when dispatching the action. This avoids the component from having to receive that data through props and has improved frame rendering by ~40%. The use of action enhancers also avoids writing utility functions to add commonly-used data to each action from action creators.
In our new architecture, the store reducers accept the dispatched action via action enhancers to update the state. The store then updates the UI, completing the action cycle. Action syncers then initiate the call to the backend APIs to synchronize local changes.
Conclusion
Our novel use of Redux in Yahoo Mail has led to significant user-facing benefits through a more performant application. It has also reduced development cycles for new features due to its simplified architecture. We’re excited to share our work with the community and would love to hear from anyone interested in learning more.
For This is Engineering Day the Royal Academy of Engineering (RAEng) released a video where they highlight all the ways different types of engineers make a difference to the world. Watch the video below.
By Idha Valeur
The second This is Engineering Day will this year happen on Wednesday 4 November 2020 as part of Tomorrow’s Engineers Week 2020 – with this year’s theme being ‘Be the difference’.
With the main aim to inspire and give more young people the opportunity to pursue a career in engineering, regardless of their background, the RAEng is now encouraging engineers, companies and organisations to get involved with the imitative to contribute ideas and ways to present how they make a difference. This could be via social media, events or other activities.
‘As young people prepare to take their key exams and think about career choices, it’s vital that they don’t miss out on opportunities to ‘Be the Difference’ though engineering just because they don’t realise what engineering careers really offer,’ the Royal Academy of Engineering Chief Executive, Dr Hayaatun Sillem CBE, said.
Sillem added that so far, more than 150 companies and organisations have already agreed to help the academy in showcasing how different and diverse the profession is. ‘We continue our work to transform the image of engineering so that many more talented young people from all backgrounds can see a future for themselves in this vital and rewarding profession.’