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 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

Carbon Emission calculation factors ?

I am thinking about writing a paper on carbon emissions based on electricity consumption data from some buildings. From a research perspective, which factors should i specially focus while...

09 October 2020 4,142 3 View

Timeout error!! Processor in the loop (PIL) using STM32F4 Matlab 2018a?

Dear Researchers I am trying to perform a PIL simulation using STM32F4 Discovery board and comunication serial USB TO TTL. During simulation I receive the following timeout error: An error...

01 March 2021 2,327 1 View

Any research papers for extraction of nutrient deprivation on macroalgae? Analysed by HPLC-UV and GC/MS. Possibly from macroalgae genus Rhizoclonium?

I am doing my thesis on the nutrient deprivation on the macroalgae Rhizoclonium sp. I will be analysing the levels over a period of roughly 5 days by HPLC-UV and GC/MS. I will be using seawater as...

28 February 2021 6,477 1 View

Necessary tube lenght to cool Natural gas in a dry-ice cooling bath?

I have a tank which contains natural gas at 250 Bar and 293 Kelvin. I want to cool the gas in a dry-ice cooling bath to about 195 Kelvin. The gas will flow in a copper-tube through the bath with a...

27 February 2021 8,128 1 View

Exit velocity of natural gas from pressurized tank?

Hi Guys. I'm a mechanical engineer and have a bit trouble, would be very glad if you could help me with my questions. I have a pressurized tank which contains Natural Gas at 200 Bar and 293...

26 February 2021 6,253 3 View

Gas sensor response and recovery time independant of flow rate and chamber volume?

I am trying to obtain the response and recovery times for my gas sensor device. It appears the the response/recovery times are primarily dependant on the flow rate of the gas I inject into the...

26 February 2021 1,511 3 View

Why do a weight decrease for thermal degradation in nitrogen gas condition?

Hi all The question is related to TGA(Thermogravimetric analysis). Thermal degradation easily understood but why do samples weight decrease? altough just binding is broked, the weight of...

26 February 2021 1,100 5 View

Why do the air flow results vary totally when adding scalar in CFD ?

Dear All, We are using Autodesk cfd to calculate the air flow in a single sided naturally ventilated room, where air flow depends only on buoyancy due to temperature difference between inside and...

25 February 2021 9,602 4 View

How to call both UMAT and UEL together in Abaqus?

I have a model with bulk material (matrix) and inclusions and cohesive interface elements between both. For the bulk material, I have implemented a UMAT and for the cohesive interface elements, I...

20 February 2021 1,286 2 View

How can we study the adsorption efficiency of microgel at the oil-water interface?

I am studing the mircogel at oil-water interface. I want to know the adsorb amount of microgel at the oil water interface. How we can determine this amount?. I will highly appreciate your...

19 February 2021 2,787 1 View

Aspen Plus Error: Unknown or undefined bead number?

Hello, in my Aspen Plus Simulation (see attachment) there are two heat exchangers. One HEX1 (oil+gas) ist fed by hot gas which ist coming out of a burner. The other HEX2 (gas+gas) shall work as a...

14 February 2021 8,096 2 View