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Operating Wisely
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
Another measure that confuses operators is mass. Mass is the amount of matter in an object. It is what one weighs at sea level under the influence of the earth’s gravity. If one is sent to Cape Kennedy, loaded into the space shuttle, sent up in space, and is then asked to stand on a scale and tell what it reads, it would be zero. With nearly zero gravity, there is no weight. However, one still has the same amount of mass that was weighed at sea level. There is a difference in weight with a change in altitude. One would weigh less in Denver, CO, USA because it is a mile higher. For all practical purposes, the small difference is not important to boiler operators. Once the fact that mass and weight have the same number on the surface of the earth is accepted (with some adjustment required for precision at higher elevations), one can accept that a pound mass weighs a pound and let it go at that.
Theoretical Aspects of Simultaneous Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA)/Differential Scanning Calorimetry (DSC)
Published in Jose James, K.P. Pramoda, Sabu Thomas, Polymers and Multicomponent Polymeric Systems, 2019
Siew Sand Chee, Mohammad Jawaid, Mohamed Thariq
In all thermobalance designs, the system will subjected to the influences of buoyancy force. The sample mass will change (increase or decrease) when it is cooled or heated on a thermobalance. The weight change is not due to the chemical or physical changes of the sample however; it is influenced by the gas density which changes as the temperature changes. When a body with a volume V is immersed in a medium (in this case a gas), it experiences an upthrust or buoyancy force, F, which corresponds to the mass of the medium displaced: F=V⋅ρ⋅g,
Geocentric Models
Published in Richard McElreath, Statistical Rethinking, 2020
In the middle plot in Figure 4.12, I show each basis function multiplied by its corresponding weight parameter. I got these weights by fitting the model to the data. I’ll show you how to do that in a moment. Again focus on the figure for now. Weight parameters can be positive or negative. So for example basis function 5 ends up below the zero line. It has negative weight. To construct a prediction for any given year, say for example 1200 again, we just add up these weighted basis functions at that year. In the year 1200, only basis functions 1 and 2 influence prediction. Their sum is slightly above the zero (the mean).
Application of compound Poisson process for modelling of ore flow in a belt conveyor system with cyclic loading
Published in International Journal of Mining, Reclamation and Environment, 2018
Piotr Kruczek, Marta Polak, Agnieszka Wyłomańska, Witold Kawalec, Radoslaw Zimroz
The proper data pre-processing is an issue that is of great importance in model fitting procedure. In order to illustrate applied procedures, the exemplary data from March 2016 are presented. The pre-processing methods for data from other months are exactly the same. The raw data are depicted in Figure 2. The measurement system acquires cumulative weight of ore mass transported through the conveyor scale. One can observe the outliers values which are present in the plot of weight. They need to be eliminated for further analysis. For this purpose, the raw data were differentiated (Figure 2(a)). Moreover, values bigger than 1 are also set to zero. The data after pre-processing are presented in Figure 3. According to cleaned data, the ore is not constantly supplied to the belt conveyor. One can notice that mine is not working during Sundays (6th, 13th, 20th, 27th of March), moreover the regular stoppages of belt conveyor are related to blasting (about 6 am and 6 pm). In the zoomed plot of the differentiated data (Figure 2(b)), one can observe the 1 tonne value related to cyclic discharging ore from the loader. Clearly, the weight should not be negative. Therefore, in order to clean data from the measurement errors, all negative values of differentiated weight data were set to zero.
Research on the parameters influencing the thermal conductivity of gypsum plasterboard under fire conditions
Published in Cogent Engineering, 2019
Plasterboard is made mainly of plaster, with the chemical formula is CaSO4. 2H2O. The composition of gypsum plasterboard consists of gypsum covered by two thin layers of cardboard paper, about 0.3 mm, on either side of the face. In some special cases, such as fire gypsum plasterboard, the gypsum core is reinforced with fiberglass, vermiculite, and clay. Fiberglass helps keep the mechanical stabilizer while vermiculite and clay are added to help reduce the shrinkage of the plasterboard when subjected to high temperatures (Thomas, 2002, 2010). The characteristics of gypsum plasterboard under the effect of high temperature are described below: In the temperature range from 30°C to 200°C: When heating the whole face of the panel already hardened, over 70°C, the water separation occurred, which destroyed the crystal lattice structure. At the temperature of approximately 200°C, the chemical water in the gypsum is completely separated. At the temperature of 200°C, the weight loss of sample is the largest (approximately 21%) due to the complete dehydration of gypsum. In the temperature range of 400–700°C: The panel has been completely dehydrated in the previous temperature range. So at this range of temperature, the weight of the sample does not change.From 900°C: If the temperature continues to rise to nearly 900°C, the following chemical reaction occurs:
Structural analysis and design of a car carrier with composite sandwich deck panels
Published in Ships and Offshore Structures, 2019
Jerolim Andric, Stanislav Kitarovic, Vito Radolovic, Pero Prebeg
Several studies covered main structural aspects and challenges in the car carrier structural design. Zanic et al. (2001) presented a case study of racking analysis of 4300 cars PCTC using the global coarse mesh full ship FE model to identify critical structural details and fine mesh FE models to solve stress concentrations problems. Amatulli et al. (2007) presented a study about accuracy of different simplified global coarse mesh FE models to be used to solve racking issues of large Ro-Ro ships in the early design stage. Tasdemir and Nohut (2012) performed fatigue analysis of the primary supporting members of 4900 cars PCTC. To make a contribution to understanding racking phenomena using full scale measurements, Soder et al. (2012) presented a method for monitoring racking-induced stresses during car carrier voyages. The approach involves real-time measurements of the ship motions and scaling of the measured motions with the pre-calculated structural response from the global FE model. A very competitive Ro-Ro market, increasing fuel cost and new more restricted emission requirements forced shipowner and shipyards to seek for the new and more efficient ships. Reduction in structural weight is one of the ways to improve ship cargo-carrying capacity. Besides structural optimisation, the use of alternative lightweight materials (aluminium, composites, plywood, etc.) and a combination of those materials can also lead to considerable weight reduction. Ringsberg (2015) presented a way to make more efficient car carriers by designing liftable deck panels using alternative materials. Comparison analysis using steel or composite liftable deck panels w.r.t weight, strength and cost has been made. Hakansson et al. (2017) investigated which fibre-reinforced polymer materials and which types of ship sub-structures are most suitable for different parts of a ship in order to minimise weight or cost. Zanic et al. (2009) presented a structural optimisation study applied to superstructure fixed decks of the Container-Ro/Ro ship as an application study within the EU FP6 project DeLight Transport. Superstructure fixed decks were designed as a combination of a deck composite sandwich panel embedded in the novel steel deck grillage supporting structure. Comparison between the novel and the conventional deck structure is given.