Selecting particular columns from large datasets (csv) using R Studio?

So I have large number of csv files (100+) in a directory with same structure and column names. The data is in time series and there are approx 30 columns/file. However i only want to aggregate...

08 February 2021 245 5 View

How can help me to Convert the files DIgSILENT PowerFactory example to an earlier version (v15.1.7)?

Hello , How can help me to convert this example files Power Factory version ,The files example from the DIgSILENT website has been created with version 15.2.5 which I do not have access to. I'd be...

31 December 2020 4,213 1 View

How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for Metabarcoding?

I'm working on pollen DNA metabarcoding to identify the floral composition of honey. How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for the...

28 December 2020 9,132 1 View

How to add two vertical and parallel Fresnel reflection coefficients to retrieve overall reflection coefficient for a right hand circular wave?

I have a problem in which a right hand circular polarized wave (GPS wave) encounters an ideal smooth plane obliquely, and then is reflected off that. To solve this kind of problems, the wave is...

28 December 2020 2,271 3 View

Which is better to focus on teaching or research for a good academic life and Why?

Which is better to focus on teaching or research for For a good academic life and Why?

26 December 2020 5,737 9 View

Is ag paste suitable for back contact on silicon wafer? or i should deposit al on the back surface using pvd or plasma sputtering?

Fabricating silicon solar cell

22 December 2020 4,906 7 View

Which renewable source is the best ?

wind hydro solar etc.

21 December 2020 6,360 16 View

Why is light pure energy?

light is pure because the light is the simplest electromagnetic construct but the energy of any object is also of the same kind.

20 December 2020 207 4 View

How to handle Missing Values for Skipped Questions (Systematic Missing) in R ?

10 December 2020 435 4 View

What is the best industrial emulsifier to make silicon oil in water emulsion?

I need to make long-lasting stable emulsions of 6 wt. % percent silicon oil in DI water. The previousely made emulsions using Tween and Span Emulsifiers did not remain stable after a week.

31 October 2020 3,568 3 View

What is the most Operating System (OS) which can be INSTALL on Tiny hard devices like Raspberry Pi (RPi) hardware ?

I'm targeting to deploy a mesh network and manually configure MANET routing protocols. I'm preparing scenarios, architectures, and hard devices needed to do that. Are there some step-by-step...

03 March 2021 1,931 5 View

Can we classify HV and LV lines based on line length?

I have dataset which shows the length of power lines. I need to classify the lines based on the line length. Is there a rule to classify the High voltage (HV) and low voltage (LV) lines based on...

03 March 2021 4,116 4 View

Irradiation data for JAPAN?

Hi, Could you help me to get the latest (2019, 2020) solar resource data for a particular site in JAPAN? PV GIS and NSRDB data are not in reach to JAPAN, I'm looking for some other database for...

03 March 2021 961 3 View

Is there a classification scheme for rock cavities or caverns with respect to their size and shape?

The range of forms and sizes of cavities in rock is very big. Is there a classification scheme for rock cavities regarding their size and shape?

02 March 2021 4,511 3 View

Ideas for Phd's Thesis on pricing (Marketing)?

Hi everyone, I'm studying Marketing and I would like to write my PhD thesis on the topic of pricing. Any specific ideas?

02 March 2021 9,706 5 View

Is there a powerful system for the security of the systems distributed on IoT systems?

Is there a powerful system for the security of the systems distributed on IoT systems?

02 March 2021 3,858 10 View

Which is suitable for use with Python? MySQL or SQL Server?

Which is suitable for use with Python? MySQL or SQL Server? What is your suggestion?

01 March 2021 3,422 3 View

How to Eliminate cosine error and abbe error in LASER measurement system(for example Rhenishaw XL80)?

I like to do project in laser measurement system. My objective is to eliminate or reduce the cosine error, abbe error in Laser measurement system. I have Rhenishaw XL80 system. Please tell the...

28 February 2021 4,890 3 View

I need dataset for recommandation system?

Hi every body I need to collect datasets from different source to work on recommendation system algorithms, could you advise me how collect data?

27 February 2021 7,063 7 View

How does an AC-DC power supply Flyback Converter Based USB Charger Model using Matlab/Simulink looks like?

I am required to learn about Flyback converters and I got stuck not knowing to full design of the power supply flyback converter Based USB Charger Model using Simulink, especially the design model...

25 February 2021 5,435 2 View