Technology
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Common problems in Autocad and their solution – a historical database
I am listing a set of AutoCAD commands and system variable which just offends the regular users. Use F1 in the AutoCAD for details. Problem: Land Desktop import slope lines in plan view Solution: To import end lines (lines meeting to ground in fill or cut): Cross section->Point Output->Catch Pt to DWG-> Yes ->…
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History of hydropower energy in Indonesia
The origins of small hydropower (SHP) in Indonesia trace back to the Dutch colonial era when the first small hydropower projects were built to supply energy for tea plantations in the 1800s. SHP development continued through the early 20th century, supplying electricity to both tea factories and the broader region. Key plants like Malabar and…
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Durability of concrete in terms of water permeability
Permeability is one of the main indicator defining the durability of the concrete. In one hand, the permeability of the concrete can be high from the beginning of concrete life, in which case, the deterioration takes place rapidly during the service life. While in the other hand, the permeability of the concrete may gradually increase…
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Degradation of concrete by abrasion
Abrasion of concrete is progressive loss of concrete mass due to mechanical degradation such as friction, grinding action, impact, overloading and local crushing. Vehicular movement and pedestrian traffic causes abrasion. The worst effect of abrasion is caused by vehicle with studded/chain tyres. Similarly, in industrial buildings, the concrete floors are subjected to impact load and…
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Derivation for sum of angles
The summation formulas for sine, cosine, and tangent are the key identities that govern trigonometric relationships. These formulas help us analyse combinations of angles in various scenarios, from simple geometric calculations to complex oscillatory systems. Let’s revise these fundamental concepts. Derivation Cos(A+B)=OP/OS=(OQ-PQ)/OS =OQ/OS-PQ/OS =OQ/OR*OR/OS-PQ/SR*SR/OS =CosA*CosB-SinA*SinB …………(since PQ=TR) Sin(A+B)=SP/OS=(ST+TP)/OS =ST/OS+TP/OS =ST/SR*SR/OS+TP/OR*OR/OS =CosA*SinB +SinA*CosB ………..(since TP=RQ) Tan(A+B)=Sin(A+B)/Cos(A+B)…
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Alkali Silica Reaction in concrete
The phenomenon of aggregates reacting with the alkali component of cement is called alkali aggregate reaction (AAR). The predominant form of alkali aggregate reaction is alkali-silica reaction (ASR) in which the silica content of aggregate reacts with sodium and potassium hydroxide of concrete. Other forms of AAR are alkali-carbonate reaction and alkali-silicate reaction. In China…
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Counting the number of words in MS-Word using Fields
Counting the number of words in MS Word document can often feel like a straightforward task—until you need to exclude certain sections like titles, references, or footnotes. Whether you’re preparing a manuscript, a report, or an academic paper, accurately tracking the word count can make a significant difference. Here’s a handy guide to help you…
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Using microbes for durable concrete
Conventionally, organic matters in concrete were considered to be undesirable. But recent study with selected microbes has shed new light on its usefulness. Both useful and deteriorating microbes has been identified. Metabolic activity of microbes produces acid which degrade concrete. These kinds of deterioration are pronounced in location having high microbial activities such as near…
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Dual effect of silica fume in concrete
While silica can cause deterioration through ASR, when used properly, it significantly enhances concrete's durability and strength