Slides for my talk on analytical modelling of energy consumption

Domestic Hot Water (DHW) is an important source of energy consumption for any type of building. I attach here the slides of a short (20 mins) talk I gave on this topic yesterday, at the Energy7 conference in Manchester UK:

Analytical modelling and prediction formulas for domestic hot water consumption – slides

I briefly outline an analytical bottom-up method to model DHW consumption accurately. We

 1) derive the correlations between occupant groups and different seasons => MAIN TREND OF CONSUMPTION
 2) generate a PREDICTIVE FORMULA for the DHW consumption of unknown occupant groups.

The slides are in PDF format (just use the pgup/pgdn keys on your keyboard to scroll). The talk is based on a paper I published last Spring, described in this entry of my blog.

Greetings from Manchester!

ON EPISTEMOLOGY OF CONSTRUCTION ENGINEERING AND MANAGEMENT

Here is the short version (conference proceedings) of our epistemology paper, discussing how Plato’s and Aristotle’s methodologies affected engineering practice, research and education during the last two centuries.

Click to access iglc-f15a7a9d-3917-4eed-ac33-1549c1719305.pdf


As a polemical side note, this shows that, contrary to some well-established pedagogical practice, you should not study at school only what you’ll need for your day job (call it Anglo-saxon, or Nordic Pragmatism).
Let me thus praise my high school formation in Italy, where three years of demanding *compulsory* philosophical studies allowed me, 20 years later, to write this paper ).

 

First material science paper now published

My paper on thermomechanical processes of charring wood is now published in Combustion And Flame. Here you can download the pdf for free for 50 days, if you are interested 🙂

In our study we develop a model for explaining the crack patterns which are formed on the wood surface when this is exposed to intense heat. It was believed for decades that such cracks are created by physicochemical processes like shrinkage, with impossibility to obtain an analytical model predicting their topology. On the contrary, we show that if one assumes the origin to be thermomechanical, the according analytical model can produce formulas which can describe and predict the crack patterns with an excellent agreement with the observations.

Here is the abstract:


In the assessment of wood charring, it was believed for a long time that physicochemical processes were responsible for the creation of cracking patterns on the charring wood surface. This implied no possibility to rigorously explain the crack topology. In this paper we show instead that below the pyrolysis temperatures, a primary global macro-crack pattern is already completely established by means of a thermomechanical instability phenomenon. First we report experimental observations of the crack patterns on orthotropic (wood) and isotropic (Medium Density Fibreboard) materials in inert atmosphere. Then we solve the 3D thermomechanical buckling problem numerically by using the Finite Element Method, and show that the different crack topologies can be explained qualitatively by the simultaneous thermal expansion and softening, taking into account the directional dependence of the elastic properties. Finally, we formulate a 2D model for a soft layer bonded to an elastic substrate, and find an equation predicting the inter-crack distance in the main crack-pattern for the orthotropic case. We also derive a formula for the critical thermal stress above which the plane surface will wrinkle and buckle. The results can be used for finding new ways to prevent or delay the crack formation, leading to improved fire safety of wood-based products.


I am now working with my colleagues on some developments of the model.

Thermal greetings to everybody!
Andrea /QP

First paper on energy efficiency published

Greetings!

My paper on theoretical modelling of daily hot water consumption in residential buildings is now published in Energy And Buildings. Here follows the abstract:

We consider Domestic Hot Water (DHW) consumption hourly data for Finnish apartments in November and August. Using datasets obtained in a previous work, we formulate a bottom-up model to quantify correlations in the consumption patterns, which are discerned by a different number of occupants for both weekday (WD) and weekend (WE). The analytical formulas thus obtained describe accurately the hourly consumption of any specific dataset. In particular, we can generate the consumption curves for unknown datasets and derive quantitatively the correlations between occupant groups and different seasons. We explain this procedure into details, define the key variables of the model and validate it against the measurements. Our quantitative results are immediately applicable to simulation tools for energy investigations and sizing of heating systems in Finland or areas with similar occupant behavior. More generally, the analytical, inductive method here introduced could be adapted to DHW studies concerning other geographic areas as well. We also argue that this simple, yet effective formalism might also be extended to other engineering contexts that are not strictly related to energy consumption. For example, the main idea could be developed and adapted to those disciplines where understanding dataset correlations constitutes an important investigation tool.


Analytical modelling and prediction formulas for domestic hot water consumption in residential Finnish apartments. Available from: https://www.researchgate.net/publication/309672534_Analytical_modelling_and_prediction_formulas_for_domestic_hot_water_consumption_in_residential_Finnish_apartments.

I will present these results in August, at the 7th International Symposium on Energy in Manchester: http://energy7.nscj.co.uk/

Energetic cheers!
Andrea /QP

 

My new cosmology paper is out!

My latest paper in cosmology is now public! It took many years to write, as it was a single author side-project on a subject that is very different from my main field. My PhD was indeed in particle cosmology, while now I am mostly working on building physics and methods for energy saving in buildings. I am however still relatively active in theoretical physics, and this is meant to be the first article of a comeback into the field.

https://arxiv.org/abs/1702.01051

Here is the abstract:

//

In the framework of MSSM inflation, matter and gravitino production are here investigated through the decay of the fields which are coupled to the udd inflaton, a gauge invariant combination of squarks. After the end of inflation, the flat direction oscillates about the minimum of its potential, losing at each oscillation about 56\% of its energy into bursts of gauge/gaugino and scalar quanta when crossing the origin. These particles then acquire a large inflaton VEV-induced mass and decay perturbatively into the MSSM quanta and gravitinos, transferring the inflaton energy very efficiently via instant preheating.
Regarding thermalization, we show that the MSSM degrees of freedom thermalize very quickly, yet not immediately by virtue of the large vacuum expectation value of the inflaton, which breaks the SU(3)C×U(1)Y symmetry into a residual U(1). Compared to the case of LLe-type inflaton previously studied, we find an even more efficient energy transfer to the MSSM quanta, due to the enhanced particle content of the supersymmetric (SUSY) multiplet that is coupled to the flat direction. Full thermalization is achieved indeed after only O(40) oscillations.
We also compute the gravitino number density from the perturbative decay of the flat direction and of the SUSY multiplet. In agreement with the literature, the inflaton produces a negligible amount of gravitinos and does not raise any cosmological issues. On the contrary, the fields to which it is coupled are responsible for a severe gravitino overproduction problem, which is caused by their large VEV-induced effective masses. We argue that possible solutions might include non-coherent oscillations of multiple flat directions or fragmentation of the inflaton condensate with formation of Q-balls.

//

Are there any issues in contemporary science and engineering?

“Are theoretical researches based on oversimplified methods which return wrong predictions? Do empiric approaches lack rigour and scientific depth? Is there any gap between theory and practice, and why?”.

Through our academic work, me and my colleagues at the Department of Civil and Structural Engineering, Aalto University, have noticed that far too often, separation of research fields and approaches results in uncorrelated work with inconsistencies and delays. This is responsible for both loss of resources and stagnation of research, which do exist in several fields. The same seemingly happens in education, as very often the students either use “cook book recipes” blindly, with no formal understanding, or dwell into the theory, with no insight of the real phenomena.

We argue that the root cause for a major part of the problems in construction engineering and management lies at the level of inappropriate choices and interpretations related to philosophy of science. Tracking this back in time, we found clues starting from the Platonic and Aristotelian contrasting approaches.

In the talk here attached I am sharing some thoughts on philosophy of science, which we are going to include in a paper now in phase of completion. Although civil engineering is our main concern, the full analysis we perform is fairly general; our results apply indeed to many other fields of engineering, and to science and technology as well (from which the title of this blog entry).

I have given this short talk (7 slides) at an Aalto workshop which took place last June. I review very synthetically the central ideas of Plato and Aristotle, and their fundamental impacts on the philosophy of science. My seminar evolves around the very basic principles of their traditions, explaining how they influenced the fundamental work of Descartes, Spinoza, Leibniz on one side, and Locke, Hume and Berkeley on the other. I also briefly mention Carnap, Popper and Feyerabend, due to their original contribution to epistemology (I deliberately avoided addressing Kant, as I will include him in a future entry on this topic).

I am not a philosopher, thus it doesn’t get too technical and everybody can understand it 🙂

Here it is: Philosophy of science: Plato vs Aristotle

P.S.: the title is set to “Plato vs Aristotle” as a necessary oversimplification: Aristotle was a disciple of Plato, and as such he maintained a deductive component in his induction-grounded science; so the opposition is not as radical and definitive as in Rationalism vs Empiricism.