Xiaoshu Lu

• PhD
• Aalto University

The article presents experimental studies of typical Finnish highly insulated (HI) envelopes with thermal resistance values ( R value) for the wall and roof inside the ventilation cavity between 7.7 and 8.1 m ² K/W and 13 m ² K/W, respectively. The conditions in the ventilation cavities were studied by using typical and increased R values for the e...

The recent research on highly insulated structures presents controversial conclusions on risks in moisture safety. This paper addresses these controversial issues through investigating the hygrothermal performance of energy efficient envelope structures under high moisture loads. The experiments consist of built-in moisture and rain leakage tests i...

Vegetable fibres are finding increasing applications in building industry due to their economic, energy and environmental sustainability. In view of utilization of insulation materials made from vegetable fibres for near zero energy buildings, this chapter presents a summary of physical, mechanical and chemical characteristics of vegetable fibres i...

Simulation models have been used widely to help design, operate, control and optimize the processes of exploration and exploitation of natural gas hydrates and been responsible for many of the most important technology breakthroughs. Currently, a rich body of literature exists and is still evolving. This paper presents a critical review of the most...

just a load of regurgite=ated nonsense

As the data-driven economy grows, we are facing unprecedented challenges of improving energy efficiency in data centers. Minimising the cooling energy demand in data centers is one of the main objectives. This paper investigates overall energy consumption and the energy efficiency of cooling system for a data center in Finland as a case study. The...

To investigate the impact of employment characteristics on the occurrence of long-term sickness absence taking socioeconomic covariates into account. A longitudinal analysis was conducted for 62,745 employees aged 18 to 64 during 1990-1999. A nonlinear random-effects model was used. In particular, the missing data patterns and their relationship wi...

Current mathematical models in building research have been limited in most studies to linear dynamics systems. A literature review of past studies investigating chaos theory approaches in building simulation models suggests that as a basis chaos model is valid and can handle the increasingly complexity of building systems that have dynamic interact...

It is useful to know ventilation rates and carbon dioxide (CO2) generation rates for evaluating indoor air quality and ventilation efficiency in mechanically-ventilated buildings. A strong limitation of the current models is either they focus solely on a whole building or they are too complicated for practical use in studies of individual spaces. T...

It is useful to know ventilation rates in order to evaluate indoor air quality (IAQ) and ventilation efficiency for mechanically ventilated buildings. A strong limitation of the current models in the literature is either they pay little attention on individual sites or they are too complicated for practical use. This paper develops a new method for...

1

This article illustrates the application of a new mathematical model developed for the study of time-dependent health outcomes for office staff during computer work. The model describes the time-dependent associations of computer usage with outcomes expressed as discomfort in multiple body regions. The association is explicitly presented with a fun...

This is the first of two articles presenting a detailed review of the historical evolution of mathematical models applied in the development of building technology, including conventional buildings and intelligent buildings. After presenting the technical differences between conventional and intelligent buildings, this article reviews the existing...

Musculoskeletal disorders are common in prolonged computer use. The dynamics of the relationship between musculoskeletal outcomes and duration of computer use is not easy to model by common statistical methods due to the nonlinearity of the data. The use of inappropriate statistical models increases the likelihood of drawing wrong conclusions. In t...

In this paper, an analysis of the diffusion behaviour of salts in fully saturated brick is presented. This paper extends the previous work to including more salt types and measurement data. Dependence of diffusion coefficient on temperature and other factors is discussed. Starting from the mathematical model which has been verified before, the obta...

A new analytical method is developed which provides close-formed solutions for both transient indoor and envelope temperature changes in buildings. Time-dependent boundary temperature is presented as Fourier series. Applying the periodic properties of the boundary condition, an approximately analytical solution for heat transfer is obtained. No num...

An analytical method is proposed to solve the equation of heat conduction in a layered sphere subject to a time-dependent boundary temperature. It is well known that for such problems in general, eigenvalue and residue computation poses a challenge, which can become too complicated to handle with many layers. In this Letter, the proposed analytical...

The analytical solution for the problem of transient heat conduction in multi-dimensional composite cylinder slab is developed for a time-dependent boundary condition. For such problems, numerical programs are needed to obtain eigenvalues and residues in most of the published papers. The numerical schemes may become unstable due to the existence of...

An analytical method leading to the solution of transient temperature filed in multi-dimensional composite circular cylinder is presented. The boundary condition is described as time-dependent temperature change. For such heat conduction problem, nearly all the published works need numerical schemes in computing eigenvalues or residues. In this pap...

In this paper a novel analytical method is applied to the problem of transient heat conduction in a one-dimensional hollow composite cylinder with a time-dependent boundary temperature. It is known that for such problems in general, the underlying eigenvalue and residue calculations pose a challenge in practice because of the computational requirem...

This paper provides an efficient analytical tool for solving the heat conduction equation in a multi-dimensional composite slab subject to generally time-dependent boundary conditions. A temporal Laplace transformation and novel separation of variables are applied to the heat equation. The time-dependent boundary conditions are approximated with Fo...

A novel analytical approach has been developed for heat conduction in a multi-dimensional composite slab subject to time-dependent boundary changes of the first kind. Boundary temperatures are represented as Fourier series. Taking advantage of the periodic properties of boundary changes, the analytical solution is obtained and expressed explicitly....

The salt diffusion in fully saturated brick at isothermal condition is investigated. A commonly used experiment methodology, diffusion cell method, is adopted to estimate the salt diffusion coefficient. The mathematical model is developed. An approximate analytical solution is given. The solution agrees with the numerical solution. The analytical s...

Thermal and moisture performances of a building system depend on the thermal and moisture behavious of the building components, the meteological conditions outside the building, and the comfort conditions required indoors. Developed by the authors, HMTB (heat and moisture transfer in buildings/structures) is a such computer tool aimed at accurately...

In this paper, a novel analytical approach to heat conduction in a composite slab subject to periodic temperature changes has been developed. Taking advantage of the periodic properties of boundary changes, the corresponding analytical solution is obtained and expressed explicitly. Unlike most of the traditional methods, it involves no residue eval...

The objective of this paper is to apply a heat and moisture transfer model in association with a proposed mathematical method to accurately predict moisture generation rates and to study the effects on the indoor moisture levels of different moisture generation rate patterns in buildings. The model is validated by a real test house. Result shows th...

The objective of this work is to evaluate the possibility of ensuring indoor temperature and relative humidity in an acceptable range by controlling heating and ventilation associated with minimising the energy consumption or cost by the use of a numerical simulation program. An acceptable indoor range means that indoor temperature is 20 °C with sm...

The overall objective of this work is to develop an accurate model for predicting heat and moisture transfer in buildings including building envelopes and indoor air. The model is based on the fundamental thermodynamic relations. Darcy’s law, Fick’s law and Fourier’s law are used in describing the transfer equations. The resultant nonlinear system...

This paper presents an investigation into salt diffusion in new, fully saturated brick under isothermal conditions. A commonly used experiment methodology, diffusion cell method, is adopted. The analytical and numerical solutions are obtained. The analytical solution is simple and straightforward, which determines temporally salt concentrations in...

The objective of this work is to evaluate the possibility of ensuring indoor temperature and relative humidity in an acceptable range by controlling heating and ventilation associated with minimising the energy consumption or cost by the use of a numerical simulation program. An acceptable indoor range means that indoor temperature is 20°C with sma...

This paper investigates the use of massive electric stove as a thermal storage in order to reduce the heating cost associated with maintaining indoor comfort condition in building. The control of electric stove takes advantage of low night-time electrical rate by shifting heating loads from day-time to night-time. A general numerical modelling of t...

Sickness absence represents a major economic and social issue. Analysis of sick leave data is a recurrent challenge to analysts because of the complexity of the data structure which is often time dependent, highly skewed and clumped at zero. Ignoring these features to make statistical inference is likely to be inefficient and misguided. Traditional...

This paper systematically investigates the time- dependent health outcomes for office staff during computer work using the developed mathematical model. The model describes time- dependent health outcomes in multiple body regions associated with computer usage. The association is explicitly presented with a dose- response relationship which is para...