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Structural Stability - Science topic

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Various test conducted for heritage masonary structure, mainly for bricks and mortar to ensure its durability and structure stability?
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The question you asked is not complete. You need to state the age (approximately) of the heritage building. This is because the tests you will need to conduct depends on the technological development at the time of construction of the heritage building.
I have transformed about a 400 years old heritage building (one of the offshoots of the Syrian empire) in Nigeria into a modern reinforced concrete building; at a time when all the building professionals concluded that the building should be replaced with a modern one. But the Emir insisted that no matter how much it costs, it should be transformed internally, while retaining the ancient preserves of his emirate. It was built with mud bricks and the suspended floor was of wood from date palms and laterite with some gravels in it. The suspended floor were of different vertical levels connected by a wooden staircase. The project was completed in 2016 within three months and with sancrete blocks wall cladding and all other exotic building components.
The transformed building was made of reinforced concrete frame structure with a new foundation, floor slab, stairs, concrete roof parapet and gutters and steel roof structure with step tile sheets or steel plate shingles.
So the age of the building to determine construction techniques used and what you intend to do now on the heritage building. You will need an AutoCad drawing of existing and proposed for architectural, Engineering (electrical, structural, mechanical) including adequate geotechnical tests, local temperatures, climate, location, rainfall pattern, etc.
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I have technical coefficients of input-output tables from 9 different years and would like to demonstrate structural stability, or lack thereof over the nine years? I can look at difference in means but looking for a more statistically rigorous analysis methodology to determine economic structural change(s) across years. The data spans about 50 years.
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Wish you luck. Regards
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Sustainable road infrastructures can boom the economy of a country. However, during my internship period as a junior engineer in Nawaloka Constructions Company Private Limited for a 72km spanning integrated road project. I have found that there were several probabilities for failure of a road rather than compared with a building construction. Because the influence of external factors like imposed loads, temperature of aggregates and bitumen, atmospheric pressure and aggregate moisture content have high influence in the structural stability of roads when compared to buildings. However, there are no any standard metrics to quantify the impact from each of the previously mentioned reasons in road constructions. Bui these type of "impact indicators" can be effectively quantified in a building construction using LCA. Due to the lack of investments, several important criteria such as LCA are limitedly accessed in only at the buildings in most of the countries like Sri Lanka. However, these semi arid zone countries are highly prone to Urban Heat Island effects (Vijayaraghavan, 2016) thus showing the necessity for the entrepreneurship to advent modern construction technologies from rural-to-urban scale. Therefore, I strongly recommend the Civil Engineering Construction firms who undertake road projects, researchers and entepreneurs to motivate the usage of LCA for every roads that needs to be constructed or needs to be evaluated on its serviceability.
I would like to know from you all that,
WHAT ARE THE DRAWBACKS PREVAIL WHEN IT COMES TO LCA IMPLEMENTATION IN ROAD CONSTRUCTIONS?
All the answers are welcomed in this healthy discussion .
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Road construction and its usage has a variety of environmental consequences. Consequently, it is critical to understand the origins of these burdens in order to implement appropriate mitigation policies. The life cycle analysis (LCA) approach is a useful tool for obtaining verifiable, accurate, and non-misleading data.
Expertise in decision-making are working "Cradle to gate as a alternative" is one such option in LCA of a provincial government.
During the long service life, the vehicle has been on the road. to take into account Construction and maintenance stages, illumination, and vehicle usage on the established road all have an impact.
As a result, it is necessary to implement ecologically friendly practises. methods for road planning, the use of low-impact procedures in material manufacture, and the usage of secondary raw materials could have the greatest influence on the environment. Therefore, it is vital to propose environmental solutions, In order to obtain a comprehensive sustainability assessment, this approach must be linked with social and economic factors simultaneously. Shuraik Kader
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hello researchers,
I have calculated the energy vs volume of my alloyin both B3 and B2 phases then ploted the curves
can we compare the structure stability of this alloy in both B3 (zinc blend structure) and B2 ( CsCl-type structure) phases, knowing that this alloy have 8 atoms in B3 phase and 16 atoms in B2 phase
my idea is divising the energies values of B2 phase on 2, then compare the two curves in the same graph
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Dear Bouchentouf Mohamed Amine
Are you working with the same compound in different structures or not?
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We have to compare two proteins (wild type and mutant) Do we have to first perform protein stability test in water MD simulation and after that for function, protein-ligand simulations? Will protein ligand md simulation be enough to predict the structural and functional stability?
Software GROMACS.
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Yes, in this way can we compare conformational changes.
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Hello,
I'm trying to figure out what are the changes to the protein structure caused by insertion of an adenine in a human gene, that causes a P->A amino acid change at the insertion site but also a shift in reading frame and insertion of a STOP further down. This should result in a truncated protein but what I would really like to know is how damaging these changes in C-terminal sequence would be in terms of protein folding and stability. I've found several tools online but none seems to do what I want or to request information I don't have. I have both the AA (or DNA) sequence of the WT protein and the same for the frameshift mutant. Data from patients suggests it could be acting as a dominant negative and, therefore, still being expressed. Sorry if this is basic, but these are not my usual swimming waters. Thanks in advance.
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It depends very much on where in the protein such a change occurs. If it severely truncates a domain or changes a majority of the domain sequence, you can be pretty sure that this domain no longer will fold properly. Domains N_terminal to the affected domain may still properly fold and even be functional. This could be a base for dominant negative effects, if such a protein e.g is still able to form heterodimers with the full length wild-type protein due to the intact N-terminal domains, but is no longer able to trigger effector functions through the domain affected by the mutation. In such a case, the mutated protein would compete with the w.t. protein. Think, for example, of a tyrosine kinase receptor with a truncation in the kinase or autophosphorylation domain. It the truncation lies beyond the transmembrane domain, the extracellular domains can show ligand-dependent dimerisation, but if only one of the two monomers contains a functional kinase, this dimerisation cannot lead to the kinase dimerisation needed for activation.
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Dear LAMMPS users
I want to calculate Mechanical properties of a carbon structure by using CH.airebo potential.
I've tried to correct potential by changing rcmin_CC and rcmax_CC, which it worked but when I increased the temperature, the structure broke down unexpectedly, I tested the structure stability by using reax potential and there was no problem. How can I correct CH.airebo potential? Any help would be appreciated.
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I also meet this problem.
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How could we relate the experimental ic50 values of ligand molecules with in-silico binding stability results?
A molecules which have a low IC50 (experimental) having high binding stability (studied by docking and dynamics), and a molecule which have high IC50 (experimental) having low binding stability. Is it ok?
I need further clarifications regarding the relation between IC50 and binding affinity!!
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It depends on the mechanism of inhibition and on the quantitative difference between "low" and "high" IC50 values. Docking scores, derived from single protein-ligand complexes rather than from their ensembles, are unlikely to correlate with IC50 values. Binding free energies obtained from molecular dynamics simulations coupled with free energy calculation (with solvent taken into account explicitly) have uncertainty limit 1-2 kcal/mol in the best case scenario.
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Here i have attached Density of states picture of cubic, orthorombic and monoclinic structure? Can anyone please help how can i relate the figure with the energy stabilization?
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Try to calculate the elastic constants of these systems and then see that your investigated elastic constant maintain the Born' stability criteria or not. If maintain then you can say that your system is stable in nature. Please never try to explain structural stability with DOS, it has nothing to do with it, instead use forces acting at each location and bondings among them, best would be the elastic analysis to reach a conclusion.
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In order to enhance the capacity, structural stability, reversibility of their cathode materials researchers used surface coating or doping. I want to know the selection criteria to select a material used as a dopant or surface coat.
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It is a matter to avoid dissolution of the transition metals componing the active cathode material into the electrolyte.
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Hi guys,
I am doing NBO analysis of my system of interest and I m taking the highest value of E(2) from output file which supposed to give the strongest stabilization but I have few queries in this regard.
1. How this E2 value stabilize the system? what is the reason behind that?
2. Has the E2 value any maximum limit for consideration (as I m getting very high value like 332 kCal/mole)?
3. In one of the cases both donor and acceptor orbitals show antibonding type showing highest E2 value? Is it possible n how? In this case the orbital occupancy of donor orbital is also slightly greater than acceptor one, is it reliable?
Can anybody explain my queries?
thanks in advance
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Most often when a column is under axial load, we say that it has bucked when we observe a decrease in the applied force (assuming a displacement controlled loading). On the other hand we know that if we consider large deflection analysis of beam-columns under axial load (elastica,Euler-Bernoulli), we see an increase in load as the displacement increases. I want to simulate this phenomenon with the help of a single simple example to enhance my understanding. I have tried with a case attached here but have been unsuccessful. Please note that I may be wrong at some points in seeking such an explanation and I will be genuinely grateful to the who comes forward to explain me where I am wrong.
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we use a beam under bending load to proof the euler classic buckling fomula for a slender culomn
If you consider the boundary conditions &
column slimming limit
ofcourse you can do that for other problems.
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It's a puzzle.
The traditional structural stability design said that in "a simetric centered compression loaded column without any eccentricity (no out of plumb), no geometrical imperfection, the called 'perfect column' would never show the buckling".
However, if it's built such a fixed-free column, for example, (not already perfect, but complying with the requirements stated before), with perfect base, plumbers, material and geometrical properties, the buckling will happen!!! Yes!
The question is: why? Enjoy the puzzle.
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Thanks Mr Arthur, for putting up a nice Puzzle and for its Ans.
Can I say, if there is no geometric or material imperfection, so called ideal column, will not fail in buckling ? Eulers buckling mode will not happen to this particular case.
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Due to the fact that the selection of a site for geological disposal is related to the stability of the geological structure, and the stability of the structure is related to the type of underground rock, how can we demonstrate the stability after disposal? We will create instability by building disposal well. And by filling it with a liquid will not provide rigid state to such a place that have rigid structure before. What instability!
Please can anyone help me understand how is it realistic?
Thanks in advance.
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Nuclear wastes are very dangerous & threats for human body due to radiation, its need to be proper dispose & management, generally it disposed on lead cylindrical dustbin, & the country government control of radiation and nuclear department are supplied necessary equipment's
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Lateral earth pressure is very important in the the estimation of retaining structures stability. Three main conditions may apear: At rest, active earth pressure and passive case. How could we determine in real field if soil is in the at rest condition?
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It can be measured using stepped blade or self-boring pressuremeter. Although these techniques are the best available ones, yet the insertion of these tools change the state of lateral stresses in the soil.
Another approach is to use the correlations of DMT, CPT and SPT to determine it or the OCR.
There are also some correlations that links the OCR to the index properties in clays that were developed by Prof. Mayne. Using the OCR, the K0 coefficient can be determined.
There are also correlations that can determine K0 or the OCR using the combined results of CPT and DMT together.
Other approaches suggest correlations of the OCR or K0 with the shear wave velocity.
I believe that the best way is use all possible approaches and reach a concluded profile of K0 based on the results of the different methods.
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Mèxico city, CDMX, is built over what used to be a lake,
I`d like to know more about the inffluence of water phreatic level on structural strength of buildings, mostly when earthquakes occur?
In terms of building structural stability, Is it better to increase or to decrease such phreatic level?
Plaese respond to gomezmancilla@gmail.com
Thanks in advance.
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Thanks for your answer. My question has a very relevant reason: the muddy soil characteristics of the terrain where it is planned to construct a new huge Mexico city, CDMX, airport. I am not a civil engineer, yet I know that seismic wave energy augments when reaching CDMX, since it is built over what it used to be Texcoco Lake. I`ve seen the hydroprofiles and its related zero pressure extends several tens of meters.
This is why I ask opinions as to what would it happen (besides sanking of the terrain) if a medium size corp of water is dissecated? I mean, modifications to the soil stiffness and other, for future earthquakes?
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I'm interested in click chemistry as a useful tool for formation of cross-linking polymers.
I applied the technique to prepare a cross-linking polysaccharide and got one successfully.
I noticed a cross-linking velocity of the preserved solution (4 ℃) was slow compared with that of the solution freshly prepared.
Although structural stability of both of DBCO- and azide-labeled polysaccharides was checked by using NMR and HPSEC, I could not find any difference in the preserved samples.
I don't know what has happened.
Please help me to solve a problem.
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Thank you so much Dr. Hanson. Could you please provide me some literature, if possible?
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Update from 1 February 2021:
I have added a new problem to be solved, named "Geometric_Stability_New_Problem3_Josko.jpg". This new problem extends the scope of the correct method to determine geometric stability into closed-loop frames and trusses.
Update from 14 January 2021: I have added a new problem to be solved, named "Geometric_Stability_New_Problem_Josko.jpg", which shows a Stable structural frame (green) and an Unstable structural frame (red). However, both frames are seemingly identical (in terms of geometry, reactions, degree of determinacy and total number of internal hinges) with the only difference being placement and design of the internal hinges. I am looking for experts who can explain why the green frame is stable but the red frame is unstable by using currently known methods and who are willing to collaborate with me in advisory role in publishing the new determination method.
The old text, from 2018:
I have developed an innovative general method which can quickly within 15-20 seconds by using hands determine geometric structural stability of every frame. The method has several advantages compared to currently existing methods such as Kennedy’s Theorem, Method of Instant Center of Rotation or others. Attached below I constructed eight examples (1-4, 5-8, geometrical lengths for all examples are either L or 2L) of complex structurally indeterminate systems and future paper draft. I am looking for potential collaborators who can explain if these systems are geometrically stable or unstable using currently known methods and who might be interested for collaboration to publish the new method together. As my background is not from theoretical structural mechanics, I am looking for experts who are willing to collaborate with me in advisory role.
"Science is the art of asking right questions instead of providing right answers."
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Dear Mohammed Lamine Moussaoui,
Thank you for the answer, it is very useful.
However, your answer answers to the question "What" is used as method, but my question is more about "How" to use existing methods. I don't think that calculating system's supports reactions is the fastest way to determine stability especially in hyperstatic systems. The method which I am planning to publish requires no longer than 20 seconds thinking time without using software, no matter how the system is complex. I an interested to compare it with currently existing methods and am seeking for experts for collaboration who know HOW to apply currently existing methods to complex structural systems, including systems 1-4 from the attachment in the first post.
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It is known that the high exchangeable Na on the exchange complex (exchangeable sodium percent) adversely affects the soil structural stability and its hydraulic properties. This impact could be minimized by high electrolyte concentration of the soil. Is there any research finding on how high should this electrolyte concentration in relation to the ESP? For instance in soils with ESP >15 what will be the difference between the influence of ECe > 4 dS/m and ECe < 4dS/m?
I have soil profile data for pH (1:2.5 soil solution), ECe (paste extract) and ESP. The soil analysis result data for each depth is given below. This profile data is from irrigated agricultural field.
0-15 cm=9.12, 7.16 and 18.11;
15-33 cm= 10.15, 3.55, 33.45;
33-74 cm=10.31, 1.56, 35.00;
74-144 cm=10.22, 1.46, 32.86 and
114-160 cm=10.19, 1.07, 35.04, respectively for pH, ECe and ESP.
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Electrical conductivity as a salient factor in saline-sodic soils of Tabriz plain
Abstract : Most of characteristic measurements of salt-affected soils are time consuming, expensive and linked with error. For this reason, some researchers have attempted to estimate those from easy-to-obtain characteristics. Electrical conductivity (EC) measurement is a means of easily quantifying salinity in salt-affected soils. Traditionally, EC of saturated soil paste extract (ECe ) has been used to assess soil salinity. This paper presents the relationships between some characteristics of saline-sodic soils and ECe in the plain of Tabriz. According to the results obtained concentration of sodium (r2 = 0.986) and chloride (r2 = 0.991) are in close double logarithmic relation with ECe . Additionally, there is a significant correlation (P<0.001) between ECe and the concentration of potassium (r = 0.83), magnesium (r = 0.84), calcium (r = 0.65) and sulfate (r = 0.79) ions. We found equations to estimate TSS and ionic strength from ECe . It was also found a power function and a double reciprocal model to describe the relationship between SAR and ECe (SAR = 1.45 ECe 0.91, r2 = 0.94) and between ESP and SAR (ESP = 1/[0.014+(1.2/SAR)], r2 = 0.94), respectively. Therefore, one can estimate ESP from ECe reliably. We also found a power function equation to estimate ECe from EC1:1 (ECe = 3.22EC1:1 0.85, r2 = 0.978). The results showed that there is a significant negative correlation between pHe and ECe (r = –0.66). After speciation, it was found relationships between ionic concentration C and corrected ionic strength with ECe . The average value of K’G for our soils was 0.00717 (mmol L-1)-0.5 and therefore lower than 0.01475 (mmol L-1)-0.5. This emphasizes the need for measurement of K’G value for any given area. In a multiple regression procedure, ECe was negatively and ESP was positively associated with K’ G (r2 = 0.61). After correction of the data for anion exclusion the average value of K’G was increased to 0.0129 (mmol L-1)-0.5 and the association was only with ESP (r2 = 0.41). PDFs enclosed..
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Hello all,
I've been trying for a while now to crosslink dopamine to chitosan using various means, more recently I have been using glutaraldehyde.
My electrode is made in house using an ink from Gwent. It seems that once printed the ink is very susceptible to attack from a variety of solvents, such as acetone, toluene, etc. I've mainly used alcohols (solvent cast) and electropolymerisation/deposit to layer my electrodes.
I've been trying to link the two amine groups of the chitosan and dopamine but have been having issues. This most recent one affects the structural stability of the working area of the electrode.
Protocol:
  1. clean in 3:1 Piranha for 15 secs, rinse x3 and dry under nitrogen.
  2. Solvent cast a co-polymer of graphene oxide and chitosan, dry in oven at 30 degrees centigrade for 1 hour.
  3. wash off excess and dry under nitrogen
  4. place working area of electrode in 5% Glutaraldehyde at 37 degrees centigrade for 2 hours.
  5. Wash off excess and dry in oven at 30 degrees centigrade for 1 hour.
Now the next step would be to incubate in a poly dopamine solution pH 9.0 at 37 degrees centigrade for 3 hours but the electrodes seem to 'crack', and lift from the substrate surface in some cases, almost slightly desiccated?
Can anyone point out the error in my protocol or offer some useful advice?
I have previously tried electrodepositing chitosan to the electrode, which resulted in uneven coating due to bubbling at the surface.
Regards,
Craig
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Dear Craig,
If your research has scientific value and intended to be published, it is better for you to discuss it within the research team you work with, because a lot of details needs to be disclosed for the right answer.
Cracking and peeling off the electrode can depend on ink composition, solvent used for rinsing, electrode material, electrode surface properties, steering type, and experimental details you may count as "default" and not important.
If not to go much into details:
- cracking means you have change of conformation of polymer film after rinsing and drying. Do you really need drying? I would try all way through using the same solvent and keep polymer wet (including storing in an exicator with solvent-vapor saturated medium) .
- your film is adsorbed on an electrode (I guess). So, electrode should have the same surface nature (hydrophilic, I think), as your polymer. If you use GC or other type of carbon, I would plasma-clean it in oxygen plasma for a few minutes, so you end up with various oxygen-containing groups on the surface. Also, make it rough with a 1000-grit sandpaper. If it is metal, I would go to Pt, not Au (I would expect better adherence), and also make it rough.
Good luck,
Ievgen
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Hey Manu,
 Are you doing flight static stability or structural stability? Sounds like structural stability from the goal. 
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The work you promised to do which has a well-defined boundary. The extent of the project or subject matter that is relevant. For example
‘we have extended the scope of our investigation’ , which means we are going to do more than our original intentions and promises.
‘such subject is beyond the scope of this book’, which means this book won’t cover such subject or the author did not intend to explain such subject.
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I need a DNA library pool to be generated using in-silico approach and have to analyze which will be more stable in conformation. In a pool of sequences, it is highly tedious to analyze structure prediction for each sequence manually. Is there any program or software available to predict structures and their stability for all DNA sequences at a time? I have come to know that Vienna RNA package can compute nearly 100 samples to the maximum at a time. Can anyone tell how to run 100 samples at a time for structure prediction? 
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The web server accepts only single sequences, but the stand-alone version accepts a file containing many sequences, as already mentioned.
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Hi all,
I am doing analytical study on behavior of chevron (eccentric) bracing with pall friction damper in RC structures using Etabs. I am looking details for mass, size and stiffness of pall friction damper connected between braces and roof. 
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Hi Shiva,
You can also try to contact the manufacturer directly. Pall Dampers are manufactured at Quaketek in Montreal (used to be built at Mechtronix), I’ve worked with them in the past in a research project.
The stiffness, mass and other parameters are well explained in https://www.quaketek.com/seismic-design/. The approximate sizes and masses are also on that page at the bottom. They have a guide for finding the optimum slip load that isn’t on their website, if you contact them they’ll probably help you out.
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A seemingly mad guess. If it were possible, according to the definition, the material might have a huge strain if we give a small pressure on it. That seems exciting for some applications such as to amplify tiny displacement?
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at the peak point of the stress-strain curve, the tangential modulus of elasticity may by equal to zero.
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What type and dimension of the specimen did you use for autoclam testing? is there any requirement for this?
Most researchers use slab of minimum 100mm depth to carry out autoclam testing but why? I'm thinking to use 150*150mm cubes or slab of 75mm depth instead but not sure whether it is good or not.
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Sorry Hung, I can't answer your question.
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Hi,
Where can I find the sources of warping constant calculation for steel sections?
Regards,
Sadjad
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Hello Sadjad,
This is given in different codes for the different section shapes. Foe example:
British Steel/Corus:
Canadian:
Nice publication from Sweden:
Best wishes
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After assembly, how could we define the concentration of tetrahedra?
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Hi
See the attached file. 
Good luck. 
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Hello,
I was wondering if there is anyone who has experience with sulforaphane. Are there any significant stability issues?
Thank you. 
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did you publish the work on sulforaphane thermal stability?
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whether curtailment of shear wall in moment resisting frame is an effective tool for resisting lateral load?
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Hello Birat Bhatta
please check pdfs
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Like, when the damage is at quarter span the reduction in natural frequency for for 4th mode is  less as compared to the frequency reduction in 2nd or 3rd mode.
Thanks 
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Dear Vipin,
From the mechanics point of view, a damage normally results in softening (i.e. reduction in stiffness), which subsequently results in a reduction in the natural frequency. However, when the damage is at or very close to the nodal point of a mode, then the negligible deformation at the modal node will shroud the softening effect and make it less visible for that mode.  This is why in your example, at quarter span you have a node for the 4th mode, but the 1st, 2nd and 3rd are quit visible at this location. 
I hope this will shed some light on the answer to your question.
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Hello, 
Good day!
I am very new to Abaqus as well as to PBC concept. I would appreciate your help to learn both of them. 
In a paper entitled "Applying Periodic Boundary Conditions in FEA" by Weidong Wu et. al. , the authors have applied PBC to a square steel plate. The applied PBC are :
                    u1left - u1right=0.01
                     u2top - u2bottom=0
Does that mean both the right and left edges will experience a displacement of 0.01? If so, why the U1 contour (attached below) is showing a value of +9.131e-03 at the bottom left corner and -1.833e-02 in the top right corner (none of the values are exactly 0.01, although they are close to it)? Could you please explain how the displacement is imposed on this body? 
My another inquiry is, is it required to prevent rigid body motion to a unit cell which is loaded by PBC like the one described above? 
Thank you! 
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Yes. You can either use the cloud version, following the manual regarding how to create user defined RVEs, or you can use ABAQUS-SwiftComp GUI. https://cdmhub.org/resources/1134 or ANSYS-SwiftComp GUI https://cdmhub.org/resources/1136. Then you can draw it using ABAQUS or ANSYS, but the GUI will call SwiftComp to perform the analysis, circumvementing all the difficulty about boundary conditions and much faster.  
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Simulation of cracks in a small structure of dam
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This is the book Design of Small Dams by Bureau of Reclamation we used in college years ago, and updated a couple of times.  It is a large document (60 MB), so don't download if you don't want detail.  I barely mentions dam cracks if that is the criteria you are seeking.. 
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I am using siesta code. in which i want to run my job at different temperature to find out the structure stability .how can i do that ?
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thanks for your kind answer.
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What all factors need to consider to estimate the stability of cement pillars kept in water?
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Dear Dr Mohan Thampi and Dr LOUIS Bertello
Thank you very much for your valuable inputs
regards
Dr Susan Verghese P
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I want to investigate the stability of two materials through phonon dispersions. I think more evidence is needed for examining the stability. Some argues that the phonon free energy provides information on the stability of crystal structure (ACS Appl. Mater. Interfaces 2015, 7, 11490-96). I am not sure if larger Helmholtz free energy means more stable structure.
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I think you have plotted the vibrational contribution to the free energy Fvib.. To get Helmholtz energy you need to add the static energy. The curves start at a positive value at T=0, which should be the zero point energy. The curves then go to increasingly negative values with the increase the temperature. This is the entropic contribution -TS.  The derivative of the curve is -S. This is NOT the phonon dispersion.
Phonon dispersion means that the vibrational frequencies change for different k-vectors. Waves that go in different directions have different frequencies. By making supercells, you calculate phonons going in a larger number of different directions.
From the graph you have shown you can see that the red structure has a larger entropy. The black has a larger zero point energy. You need to add the static electronic energy to see the free energy and the relative stability between them.
And "thermodnamically stable" does NOT mean that there are no imaginary frequencies! It just means that the structure is a local energy minimum. Thermodynamically stable means it is the global minimum.
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Researchers in the field of crashworthiness analysis.
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The question might be: why should I use a quasi static test instead on an impulse test for real time impact? Is the impact destructive or elastic?
An elastic impact or impulse test deals with a complete description of the structural dynamics, which can not be described by a quasi static test only. It's like using only the stiffness matrix in a MDOF system, forgetting the damping and mass matrices, thus the eigenmodes and all the modal descriptors.
If you work in the frequency domain, then the dynamic response of a structure close to zero-frequency should be comparable to quasi static test. But the characterization of the complete dynamics is the way to answer the problems in impacts until you are in elastic behavior. 
If you observe plasticity, then more complex non-linear models should be considered for the whole dynamics, which results in tougher calculations.
Hope this helps,
Alessandro
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increasing the depth of Raft foundation settlement should be minimum. But at certain limit increasing the depth of raft settlement slightly increases . is it true or why it happens ? Type of soil is sandy its sub-grade modulus is 150 kn/m3
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Dear,
SAFE 12 is not able to predict total settlement, yet you can use it for differential settlement, i hope this would solve the problem
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Dear all:
I apply ABAQUS to model a steel bar under compressive load, and use displacement control, but the result showed that at the beginning it was compressed, but later on, it was stretched and the structure is tending to deform unreasonable, see the attached picture, can any one do me a favor and tell me what is the reason of that?
Sincerely yours,
Mengli
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You should create a constraint as follows:
In the interaction module of Abaqus/CAE, select Create Constraint-> Coupling, select a node at the middle of the surface, define the surface to be node based, then at the window that appears select Coupling type to be Kinematic. Do this for the loaded and the constrained end of the solid beam.
After this you can apply a pin constraint at the reference point of the one end of the beam, and a load (force or moment) at the reference point of the constraint of the other end of the beam.
I tried the above and they work. Of course, there may be other options to impose the conditions you want, of lower or higher complexity.
I hope this helps.
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I have recently read articles about the biochemical characterisation of proteins, and see people use dimer stability, structural stability and thermal stability, I wonder what's the differences between these terms?
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Of course dimer will be more stable than monomer as its dissociation will require an added energy input to break up interaction forces. Further, most of the time, dimerization/oligomerization also induces some structural rearrangments resulting into a more stable conformation of the monomer.
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At what temperature? Also, if there is any article that can back up the answer? Thank you!
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thank you so much!
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I have a student working on the lateral torsional buckling of truss girders. He is struggling to find any documents in the literature. Any pointers will be very welcome.
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I suggest you the paper "CALCUL DES CONTRAINTES DANS UN ÉLÉMENT
SOUMIS À DE LA TORSION" by  S. Baraka and A. Bureau, revue construction métallique, CTICM;  is joint as attached file. 
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How are strength value(s) of a wood adhesive computed?
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thanks alot @Rafik
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How to distinguish, define and analysis the "material stability" and the "structure stability" in mathematics, computation or engineering applications? Thanks!
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Yes, when the stress at a material point of a structure reaches the critical stress (or energy critierion), the structure would be destroied, which shows the structure instability. However, when the structrue is destroied, is that critial material point destroied too? Could we think about the material instability happens before the structure instability in this case? 
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When i define frame and wall interface, i use CSC model in diana. It is working because force is transferred but it looks like wall is penetrating frame. What may be the reason for this problem??? 
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This can be due to the above mentioned reasons. But please first make sure that this is not a graphical error and the wall is really penetrating. For controlling this you can compare the X-direction displacements of the node on the corner of the wall with the one in the same position on the column. Please check the difference between them and see if the X-displacement of the point on the column is more than the wall corner.  
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Usually the minimum thermal conductivity (kmin)indicates the high temperature thermal conductivity of an insulator when the mean phonon free path is close to the interatomic distance. The minimum thermal conductivity of Clark and then modified by Liu have been widely used to predict the kmin of a number of oxides. (1.D. R. Clarke, “Materials Selection Guidelines for Low Thermal Conductivity Thermal Barrier Coatings,” Surf. Coat. Technol., 163–164, 67–74 (2003). 2.B. Liu et al “Theoretical Elastic Stiffness, Structure Stability and Thermal Conductivity of La2Zr2O7 Pyrochlore,” Acta. Mater., 55, 2949–57 (2007).) 
However, I just read a paper published in Chin. Phys. B, see the attached, that calculates the kmin of electrical conducting materials of M4AlC3. Since there is electronic contribution to the thermal conductivity, my question is :are these authors calculated are real minimum thermal conductivity?
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Hi Yanchun,
they are calculating only the phonon component of the thermal conductivity and obtain numbers in the ball-park 1-2 W/(m*K). I'd expect the electronic contribution to be dominant, say 5-10 times larger than that.
The approach they used only works for materials where the phonon thermal conductivity is dominant.
Per
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The polymer is a type of PDMS elastomer which will have crosslinking by heating. 
The oil is less dense than the polymer, hence may separate due to density difference.
The oil has a quite low viscosity, lower than typical cooking oil.
They are mechanically mixed before heating, after that elevated heat is applied for the PDMS crosslinking.
As mentioned, the polymer can be crosslinked but the polymer system is not expected to chemically react with the oil. Mass of oil ~ 30% of the total mass of blend. 
As far as I know, PDMS and oil are immiscible hence may have phase separation later after mixing, not to mention the effect of density difference. However, crosslinking of PDMS may stabilize the blend. I found that if oil mass is ~50% of the total blend, the phase separation appears rather quickly (visible by naked eye), even before heating is applied and the bulk of PDMS crosslinking happens.
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Sorry, but you did not mention the type of oil you use. If it is natural oil, there are numerous types as to plant, region, year of harvest, quality of production, ageing etc. Any of these factors will change the miscibility. If you use mineral oil the degree of branching and mol weight are essential. Next, the hydrophobic character will have an effect, so you have to test e. g. castor oil, rape seed oil, soy bean oil, linseed oil etc for their miscibility. In case of silicone rubber you'll have to test several to find one type of oil being miscible - which depends on the type of the silicone rubber (which side groups to which extent?). You can also try by introducing a solubility enhancer such as 2-ethyl-1,3-hexane diol or higher branched diols...
The work of Dr. Vesela Stoycheva was published in a presentation at TH Wildau in German and in their Wissenschaftliche Beiträge, I think in 2013, but you'll find it in research gate (if not, search fpr Michael Herzog) or in her Ph. D. Thesis which is in Bulgarian.
If further questions in this respect you may diretly contact her at vesela.stoycheva@th-wildau.de
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I found a study in Protein Engineering, they mentioned two parameters: RMSD (with comparison to the crystal structure) and the stability of the second structure elements. It's a kind of old study though; that's why asking if there is something else I should look at.
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Assalamo Alaykom,
Mohanmed,
Stability is a very broad concept and there is no universal way of telling whether your protein is stable or not. In your case, I would suggest running two simulations, one with the native protein and one with the modified one and compare several parameters including RMSd, any critical angles or dihedrals that you know a proiri about their significance, also check energy convergence (both potential and kinetic). You may also superpose the two proteins and comment about any major deviations between the two structures.
It is always a good idea to try to find an innovative smart way of telling whether your protein is stable or not. This is better than checking literature and trying to find a universal measure of stability.
Ahmed
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this is a silly question but I want to know that, what is the relationship between the protein beta sheets and structure stability?
and another question is is there any fix region for alpha helix and beta sheet in Ramachandaran Plot? 
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There is no direct correlation between stability and percentage of beta strand and helix secondary structure. However, highly alpha-helical protein frequently are less problematic upon unfolding, proteins with high beta strand propensity are more likely to form amyloid-like aggregates.
See here for the regions of the ramachandran plot corresponding to the different  secondary structures: http://www.cryst.bbk.ac.uk/PPS95/course/3_geometry/rama.html or simply consult wikipedia http://en.wikipedia.org/wiki/Ramachandran_plot
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A foundation resting on soil reinforced by floating stone or sand columns?
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You have several methods. One is the one Keller recommends for computing the equivalent overall mechanical parameters using Priebe's method. You can find it here: http://www.getec-ac.de/download/en/pdf/GT07-13E.pdf
Another way is to use any FEM analysis and consider the stone columns as such, with proper interaction with the adjacent soil.
A third method, if you intend to have a gradual change of mechanical parameters from the column axis to the soil, is to use the thermal dependence trick, namely consider a homogeonous medium with parameters variable with temperature so that a 0 degrees you have soil parameters and at 1 degree you have the stone column parameters.  You control the linear variation in the zones with temperatures between 0 and 1, you have the columns in the zones with 1 degree and the rest of the soil remains at 0. If you want to pursue this path I can give you additional info.
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Far UV CD, tryptophan fluorescence and SEC was used to confirm the results.
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Carbonic Anhydrase has been reported to be quite stable over a wide range of pH: between pH 4.0 and pH 11.0 - although not as low as pH 2.0. Its thermal stability and folding has been studied in some detail by a Swedish group.
Martin Karlsson, Lars-Göran Mårtensson, Bengt-Harald Jonsson, and Uno Carlsson.
You may want to read some of their publications.