bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of the rate of surface dilatation in determining microscopic dynamic contact angle
Authors: Thalakkttor J. J. , Mohseni K.
Published: January 2020

The factors determining the degree of dynamic wetting, which is characterized by the microscopic dynamic contact angle, have been the subject of much discussion. In this manuscript, it is analytically determined that the microscopic dynamic contact angle is dependent on the rate of surface dilatation in addition to the thermodynamic surface tension. It is argued that, in the vicinity of a moving contact line, this rate of surface dilatation results in a disparity between the thermodynamic and mechanical surface tensions, which are almost always assumed to be equal. It is also found that, in the case of forced wetting, the difference between the receding and advancing contact angles is primarily due to the rate of surface compression at the receding contact line and the rate of surface expansion at the advancing contact line. These findings, which are validated using molecular dynamics simulations, demonstrate that surface dilatation is an important factor responsible for the deviation of the microscopic dynamic contact angle from its static equilibrium value.
The influence of hydrodynamic effects on the complex susceptibility response of magnetic fluids undergoing oscillatory fields: New insights for magnetic hyperthermia
Authors: Guimarães A. B. , Cunha F. R. , Gontijo R. G.
Published: January 2020

In this work, we perform Langevin dynamics simulations to examine microstructure-macroscopic related properties of magnetic fluids in an attempt to understand the influence of the long range viscous hydrodynamic and dipolar interparticle interactions on the complex susceptibility response of a magnetic suspension undergoing an oscillatory magnetic field. The simulations use periodic boundary conditions in order to properly compute particle interactions through the Ewald summation technique. The imaginary part of the complex susceptibility predicted by the simulations is presented in terms of the frequency, particle volume fraction, and Péclet number. This property is used to investigate the process of magnetic hyperthermia. A detailed comparison between our simulations and the prediction of an asymptotic theory for a small Péclet number in the absence of hydrodynamic interactions shows an excellent agreement. The influence of the hydrodynamic and dipolar interactions on the average rate of temperature rise is investigated here. The coupling between the particle relaxation time and the forcing frequency of the applied field is also discussed. The simulations exhibit inhomogeneous chainlike structures in the numerical box induced by interparticle dipolar interactions. We find that the presence of these structures enhances magnetic heating production, whereas hydrodynamic interactions weaken this effect. Our results also suggest that the way of combining and controlling physical parameters at moderate frequencies of the applied oscillatory field can improve the heating performance of magnetic hyperthermia.
Positron emission particle tracking using machine learning
Authors: Nicuşan A. L. , Windows-Yule C. R. K.
Published: January 2020

We introduce a new approach to positron emission particle tracking based on machine learning algorithms, demonstrating novel methods for particle location, tracking, and trajectory separation. The method allows radioactively labeled particles to be located, in three-dimensional space, with high temporal and spatial resolution, requiring no prior knowledge of the number of tracers within the system and can successfully distinguish multiple particles separated by distances as small as 2 mm. The technique’s spatial resolution is observed to be invariant with the number of tracers used, allowing large numbers of particles to be tracked simultaneously, with no loss of data quality.
Turbulent drag modification in open channel flow over an anisotropic porous wall
Authors: Li Qingxiang , Pan Ming , Zhou Quan , Dong Yuhong
Published: January 2020

Direct numerical simulations are carried out for incompressible viscous turbulent flows over a porous wall with reduced spanwise permeability. This paper is intended to examine how the anisotropy of a porous wall affects the turbulence characteristics and modifies the skin-friction drag and to demonstrate numerically how sensitive the turbulent drag is to the porous layer thickness in channel flows. Simulations are carried out at a friction Reynolds number of 180, which is based on the averaged friction velocity at the interface between the porous medium and the clear fluid domain. The thickness of the porous layer ranges from 0.9 to 54 viscous units. For each fixed permeability, the drag is observed to decrease for flow over the porous layer with a smaller thickness hp, while a drag increase occurs for a larger hp. The division between two regimes (drag-reducing and drag-increasing) highlights a critical roughness height hc*, which depends linearly on the spanwise permeability Reynolds number as hc* ∼ Rekz. A larger value of hc* suggests an increasing degree of drag reduction can be achieved in a relative wider range of the porous layer thickness. For the porous medium configurations considered, the maximum drag reduction rate obtained is about 20.3% at hp+=9 (hc* = 18.3, Rekz = 0.18).
Conditions for stable equilibrium in Cournot duopoly models with tax evasion and time delay
Authors: Villafuerte-Segura Raúl , Alvarado-Santos Eduardo , Itzá-Ortiz Benjamín A.
Published: January 2020

We provide conditions for stable equilibrium in Cournot duopoly models with tax evasion and time delay. We prove that our conditions actually imply asymptotically stable equilibrium and delay independence. Conditions include the same marginal cost and equal probability for evading taxes. We give examples of cost and inverse demand functions satisfying the proposed conditions. Some economic interpretations of our results are also included.
Multiferroic behavior from synergetic response of multiple ordering parameters in BiFeO3 single crystal under high magnetic field up to 50 Tesla
Authors: Huang Sha , Hong Fang , Xia Zhengcai , Yang Feng , Zhang Xiaoxing , Xiao Guiling , Song Yujie , Jiang Dequan , Deng Han , Ouyang Zhongwen , Wang Junfeng , Tian Zhaoming , Han Junbo , Yao Linhua , Forget A. , Colson D. , Cheng Zhenxiang
Published: January 2020

BiFeO3, a typical multiferroic compound, owns complicated interactions among its charge, lattice, and spin degrees, while largely remaining a mystery. In this work, the BiFeO3 single crystal has been investigated in pulsed high magnetic fields up to 50 T. The lattice, spin, and charge orderings are found to couple with each other strongly. High magnetic field could drive the spin cycloid phase to a canted antiferromagnetic phase while accompanied by a clear magnetostriction response and weakening of ferroelectric polarization. The critical magnetic field for the magnetic phase transition was shifted to the lower magnetic field region by an external electric field over a broad temperature range, which indicates the complex interaction among magnetization, electrical polarization, and crystal lattice. This work has provided a clear picture to show the synergetic response of multiple ordering parameters during the magnetic phase transition in BiFeO3, which could benefit the design of BiFeO3 based spintronic devices and novel multiferroic materials with strong magnetoelectric coupling.
Evolving data standards for cryo-EM structures
Authors: Lawson Catherine L. , Berman Helen M. , Chiu Wah
Published: January 2020

Electron cryo-microscopy (cryo-EM) is increasingly being used to determine 3D structures of a broad spectrum of biological specimens from molecules to cells. Anticipating this progress in the early 2000s, an international collaboration of scientists with expertise in both cryo-EM and structure data archiving was established (EMDataResource, previously known as EMDataBank). The major goals of the collaboration have been twofold: to develop the necessary infrastructure for archiving cryo-EM-derived density maps and models, and to promote development of cryo-EM structure validation standards. We describe how cryo-EM data archiving and validation have been developed and jointly coordinated for the Electron Microscopy Data Bank and Protein Data Bank archives over the past two decades, as well as the impact of evolving technology on data standards. Just as for X-ray crystallography and nuclear magnetic resonance, engaging the scientific community via workshops and challenging activities has played a central role in developing recommendations and requirements for the cryo-EM structure data archives.
Entangled two-photon absorption spectroscopy for optically forbidden transition detection
Authors: Oka Hisaki
Published: January 2020

We theoretically propose a spectroscopic method for measuring optically forbidden states using entangled two-photon absorption (TPA). As a model system, we consider a diatomic molecular system consisting of three adiabatic potentials, namely, ground, intermediate, and excited states, where the intermediate state cannot be directly excited from the ground state. In our method, we pump the excited state using entangled TPA and indirectly measure the optically forbidden intermediate state through the photon emission from the excited state to the intermediate state. The condition required for this method is only that the transition rate between the excited and intermediate states is sufficiently high. Using our proposed method, we show that the optically forbidden state can be detected with a high degree of accuracy when highly efficient and selective TPA is realized.
Machine learning is used to conduct positron emission particle tracking
Authors: Mandel Savannah
Published: January 2020

Positron emission particle tracking using machine learning offers crucial biomedical applications, such as the study of blood flow and the study of gastrointestinal circulation.
Using machine learning to extract coarse-scale PDEs from fine-scale data
Authors: Liebendorfer Adam
Published: January 2020

Combining techniques such as Gaussian processes and neural networks with feature selection and manifold learning approaches yields broad possibilities for improved data-driven modeling.
Designing effective control of dengue with combined interventions
Authors: Hladish Thomas J. , Pearson Carl A. B. , Toh Kok Ben , Rojas Diana Patricia , Manrique-Saide Pablo , Vazquez-Prokopec Gonzalo M. , Halloran M. Elizabeth , Longini Ira M.
Published: January 2020

Significance

Using realistic simulation of dengue and plausible control programs in the state of Yucatán, Mexico, we show that vaccination programs can have amplifying or interfering dynamic effects when combined with expanded vector control effort. These results should inform planning in regions considering an integrated dengue control program, particularly if using CYD-TDV, which we found to underperform when combined with increasing vector control.
Molecular adaptations of the blood–brain barrier promote stress resilience vs. depression
Authors: Dudek Katarzyna A. , Dion-Albert Laurence , Lebel Manon , LeClair Katherine , Labrecque Simon , Tuck Ellen , Ferrer Perez Carmen , Golden Sam A. , Tamminga Carol , Turecki Gustavo , Mechawar Naguib , Russo Scott J. , Menard Caroline
Published: January 2020

Significance

Thirty to fifty percent of depressed individuals are unresponsive to commonly prescribed antidepressant treatments, suggesting that biological mechanisms, such as stress-induced inflammation and blood vessel dysfunction, remain untreated. The blood–brain barrier is the ultimate frontier between the brain and harmful toxins or inflammatory signals circulating in the blood. Depression and vulnerability to chronic social stress are associated with loss of this barrier integrity; however, the mechanisms involved remain poorly understood. Identification of adaptations leading to resilience under stressful conditions could help develop novel treatments. Here we combined behavioral, pharmacological, and cell-specific gene profiling experiments in mice with epigenetic, molecular, and anatomical analysis of human samples to unravel mechanisms with therapeutic potential to protect the brain and promote resilience.
Release of a disordered domain enhances HspB1 chaperone activity toward tau
Authors: Baughman Hannah E. R. , Pham Thanh-Hau T. , Adams Chloe S. , Nath Abhinav , Klevit Rachel E.
Published: January 2020

Significance

Molecular chaperones defend against protein aggregation that can otherwise lead to many diseases, including Alzheimer’s disease and related dementias. The small heat shock protein (sHSP) chaperones are underappreciated in large part because we lack insight into the mechanisms by which they defend against protein aggregation. This study of how the sHSP HspB1 delays aggregation of the Alzheimer’s-linked protein tau leads to a model in which the release of a sequestered disordered region of the chaperone greatly enhances its activity. The model reveals a general mechanism by which sHSPs can be activated and suggests a strategy by which this interaction could be exploited therapeutically.
Dictionaries and translation
Authors: Hlebec Boris
Published: January 2020

The article offers a bird’s-eye view of the use of dictionaries in translation, accompanied by down-to-earth
exemplifications of the arguments. After propounding the essential difference between a bilingual dictionary and translation, a
brief survey follows of problems that should be solved by both. They include the treatment and translation of technical and
literary texts, of collocations, phrases and idioms, of colloquial, slang, dialectal, dated and obsolete words, of neologisms and
nonce-words. Mention is also made of the problem of treating application. As a onclusion, translators may be given a piece of
advice: Think of a dictionary as a counsellor and a friendly aide, but complement it with other sources of information and do not
always rely upon it.
An argumentative reconstruction of the computer metaphor of the brain
Authors: Finsen Andreas Bilstrup , Steen Gerard J. , Wagemans Jean H. M.
Published: January 2020

The computer metaphor of the brain is frequently criticized by scientists and philosophers outside the computational paradigm. Proponents of the metaphor may then seek to defend its explanatory merits, in which case the metaphor functions as a standpoint. Insofar as previous research in argumentation theory has treated metaphors either as presentational devices or arguments by analogy, this points to hitherto unexplored aspects of how metaphors may function in argumentative discourse. We start from the assumption that the computer metaphor of the brain constitutes an explanatory hypothesis and set out to reconstruct it as a standpoint defended by a complex argumentation structure: abduction supported by analogy. We then provide three examples of real arguments conforming to our theoretically motivated construction. We conclude that our study obtains proof-of-concept but that more research is needed in order to further clarify the relationship between our theoretical construct and the complexities of empirical reality.
The SDGs and the bio-economy: fostering land-grabbing in Africa
Authors: Ashukem Jean-Claude N.
Published: January 2020

This article analyses the contributory role of the bio-economy and the UN General Assembly Sustainable Development Goals in facilitating and fostering land-grabbing in sub-Saharan Africa. It argues that with the rapidly increasing demand for land and the use of agricultural produce for food and energy purposes, the bio-economy, together with the Sustainable Development Goals, has inexorably exacerbated the practice of land-grabbing in sub-Saharan Africa, where land is considered to be abundant, empty and unused. Sub-Saharan Africa has again been perceived primarily as a steady supplier of land for the production of food and non-food crops.
An integrated approach to managing Rhizoctonia solani on maize in marginal soils: field studies
Authors: Kubheka Bongani Petros , Laing Mark Delmege , Yobo Kwasi Sackey
Published: January 2020

A study was conducted over two seasons in a marginal soil with an acid saturation of 54%. A plant growth promoting rhizobacterium, Bacillus megaterium, a commercial biocontrol agent, Trichoderma harzianum Strain kd (Eco-T®), and soluble potassium silicate
were used in this study. The objective was to control maize yield reduction caused by Rhizoctonia solani AG2 root rot isolated from infected maize. R. solani reduced maize yields significantly by 34% in the first season. However, the losses decreased in the second season
from 34% to 10%. In the first season, combination of T. harzianum, B. megaterium and potassium silicate increased maize yields by 130%. The highest yield in the presence of R. solani was treatments with T. harzianum (216%) followed by T. harzianum plus potassium
silicate (214%) and lastly T. harzianum plus B. megaterium (178%). However, in the second season, T. harzianum plus potassium silicate treatment resulted in the highest yields.
Investigating the effect of bouncing type on the physiological demands of trampolining
Authors: Clement Tane , Alexander Keith , Draper Nick
Published: January 2020

Purpose: The aim of this study was to investigate whether altering the bounce style affects the physiological demands of trampolining.

Methods: Twenty‐eight healthy adults completed five, three‐minute exercise bouts on a trampoline where; heart rate (HR), (mL/min) and rate of EE (kJ/min) were collected for five different bouncing variations.

Results: A one‐way repeated measures MANOVA was then used to assess whether significant differences existed between the different bounce types for HR and EE. A significant difference was found ( = 20.886, p = 0.0005), so a series of one‐way repeated measures ANOVAs were used to identify the degree of significance. For ( = 64.079, p = 0.0005, ηp 2 = 0.7) and EE ( = 44.979, p = 0.0005, ηp 2 = 0.6). Post‐hoc tests found that for both and EE a significant difference existed between the conventional bounce and each of the bounce variates (p = 0.0005).

Conclusion: The results from this study indicated altering the bounce style does have a significant effect on the physiological demands of trampolining. The energy expenditure (EE) equation for trampolining can now be updated to more accurately reflect the rate of EE while performing different bounce styles.
Macrophage galactose lectin is critical for Kupffer cells to clear aged platelets
Authors: Deppermann Carsten , Kratofil Rachel M. , Peiseler Moritz , David Bruna A. , Zindel Joel , Castanheira Fernanda Vargas E Silva , van der Wal Fardau , Carestia Agostina , Jenne Craig N. , Marth Jamey D. , Kubes Paul
Published: January 2020

Every day, megakaryocytes produce billions of platelets that circulate for several days and eventually are cleared by the liver. The exact removal mechanism, however, remains unclear. Loss of sialic acid residues is thought to feature in the aging and clearance of platelets. Using state-of-the-art spinning disk intravital microscopy to delineate the different compartments and cells of the mouse liver, we observed rapid accumulation of desialylated platelets predominantly on Kupffer cells, with only a few on endothelial cells and none on hepatocytes. Kupffer cell depletion prevented the removal of aged platelets from circulation. Ashwell-Morell receptor (AMR) deficiency alone had little effect on platelet uptake. Macrophage galactose lectin (MGL) together with AMR mediated clearance of desialylated or cold-stored platelets by Kupffer cells. Effective clearance is critical, as mice with an aged platelet population displayed a bleeding phenotype. Our data provide evidence that the MGL of Kupffer cells plays a significant role in the removal of desialylated platelets through a collaboration with the AMR, thereby maintaining a healthy and functional platelet compartment.
The C/O ratio of He-accreting carbon-oxygen white dwarfs and type Ia supernovae
Authors: Cui Xiao , Wang Bo , Wu Cheng-Yuan , Meng Xiang-Cun , Han Zhan-Wen
Published: January 2020

Type Ia supernovae (SNe Ia) are thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs), and are believed to be excellent cosmological distance indicators due to their high luminosity and remarkable uniformity. However, there exists a diversity among SNe Ia, and a poor understanding of the diversity hampers the improvement of the accuracy of cosmological distance measurements. The variations of the ratios of carbon to oxygen (C/O) of WDs at explosion are suggested to contribute to the diversity. In the canonical model of SNe Ia, a CO WD accretes matter from its companion and increases its mass till the Chandrasekhar mass limit when the WD explodes. In this work, we studied the C/O ratio for accreting CO WDs. Employing the stellar evolution code MESA, we simulated the accretion of He-rich material onto CO WDs with different initial WD masses and different mass accretion rates. We found that the C/O ratio varies for different cases. The C/O ratio of He-accreting CO WDs at explosion increases with a decreasing initial WD mass or a decreasing accretion rate. The various C/O ratios may, therefore, contribute to the diversity of SNe Ia.
Assessment of miniaturized ultrasound-powered implants: an in vivo study
Authors: Vo Jesse , Chang Ting Chia , Shea Katherine I , Myers Matthew , Arbabian Amin , Vasudevan Srikanth
Published: January 2020

Objective. Therapeutic applications of implantable active medical devices have improved the quality of patient life. Numerous on-going research in the field of neuromodulation and bioelectronic medicine are exploring the use of these implants for treating diseases and conditions. Miniaturized implantable medical devices that are wirelessly powered by ultrasound (US) can be placed close to the target sites deep inside the body for effective therapy with less invasiveness. In this study, we assessed the long-term in vivo performance of miniaturized US powered implants (UPI) using a rodent model. Approach. Prototype UPI devices were implanted in rodents and powered wirelessly using an unfocused US transmitter over 12 weeks, and the corresponding device output was recorded. Structural integrity of UPI before and after implantation was studied using scanning electron microscopy (SEM). We also conducted qualitative histological assessment of skin and muscle surrounding the UPI and compared it to naïve control and US exposed tissues. Main results. We found that it is feasible to power UPI devices wirelessly with US over long-term. The encapsulation of UPIs did not degrade over time and the tissues surrounding the UPI were comparable to both naïve control and US exposed tissues. Significance. This study is the first to assess the long-term performance of miniaturized UPI devices using a rodent model over 12-weeks. The set of tests used in this study can be extended to assess other US-powered miniaturized implants.
On the definition and prioritization of strategies and actions to minimize greenhouse gas emissions in cities: An actor-oriented approach
Authors: Balouktsi M , Lützkendorf T
Published: January 2020

Cities as hotspots of human economic activity and infrastructures provide some of the best opportunities for decarbonizing sectors essential for limiting the global warming to 1.5, such as buildings and transport. For this reason, regulators and researchers have widely recognized the necessity to put cities, as an important object of assessment, and city authorities, as an important actor group, at the core of climate mitigation efforts. In their pursuit of a low-emission future, however, cities are confronted with a number of theoretical and practical questions regarding allocation and accounting of city-related greenhouse gas (GHG), target setting and subsequent planning for mitigation. A wide literature is currently focused on the first two. However, to achieve ambitious climate targets, research should urgently focus more on how to reap all available urban mitigation actions and encourage rapid and radical changes. Identifying and prioritising mitigation strategies and actions to achieve the targets, as well as putting them together into a coherent plan with a clear vision of the future, are critical steps in actionable and effective climate action planning. As a first contribution in this direction, this paper provides recommendations for research and practice to support a more integrated and conscious definition and prioritization of actions by municipal stakeholders, based on: (1) the specific context of each city type as a determinant of what actions may work, (2) the executive power of city authority to act as the main actor and (3) the multiple benefits and/or trade-offs accruing from each local climate action.
Towards climate change mitigation and adaptation in cities – the role of Greek Municipalities and Prefectures. Findings and outcomes from the EMPOWERING Project.
Authors: Theodoridou Ifigeneia , Mermigas Andreas , Christodoulou Aikaterini , Kanouras Spyridon , Kokkinidou Rania
Published: January 2020

Climate change is a global challenge that must be tackled in order to secure a safe planet for the young generations, as it threatens Europe’s ecosystems, human health and economy. In this line, the European Union is focusing on a strict 2030 energy agenda in order to achieve a climate-neutral Europe by 2050, in line with all necessary reductions by developed countries as a group and at the same time make a fair and ambitious contribution to the Paris Agreement. Since, 70% of cities are already dealing with the effects of climate change, along with their rapid growth and the high intensity of urban sprawl, Local Authorities’ role is of vital importance. Moreover, besides environmental and social related factors that drive the battle against climate change, economic parameters represent key drivers of CO2 emissions’ reduction policies. In this framework, the most important initiative on a European Level, is the Covenant of Mayors – CoM that was created in 2008 and gathers more than 9.660 signatories globally that have voluntarily committed to create Sustainable Energy and Climate Action Plans (SECAPs). In this line, the EMPOWERING Project, launched in 2017, aimed at supporting Local Authorities enhance their capacity in terms of planning efficient energy measures within the new European 2030 framework for Climate and Energy Policy. This research presents the main results and conclusions of the authors’ technical support to the Region of Central Macedonia (RCM) and its participating municipalities.
High performance building façades for Zero Energy Buildings in Greece: State of the art and perspectives
Authors: Antoniadou Panagiota , Symeonidou Maria , Kyriaki Elli , Giama Effrosyni , Boemi Sofia-Natalia , Chadiarakou Stella , Papadopoulos Agis M.
Published: January 2020

Pursuing high energy performance with the least environmental impact of a building, along with ensuring the well-being of the occupants, is the ultimate goal of an institutional framework that addresses energy efficiency and environmental sustainability. The building sector is responsible for 38% of the total final energy consumption in Europe and is therefore in the epicentre of the effort to achieve improvements. This is being expressed by the targets of EU policies for 2030 and 2050, which set truly ambitious goals.

Part of this effort is the improvement of the building’s envelope thermal performance, along with the respective one of the HVAC systems, but also integrating those two in the best possible way. The façade is the crucial factor, as it is the interface between the building and its environment, but also between the environment and the HVAC system; it is truly the building’s skin, which is therefore much more than a simple state boundary, if we want to have truly advanced buildings. Main scope of the paper is to present the results of an in depth investigation regarding the best available technologies and the upcoming trends of intelligent building façades, to be used in Zero and Positive Energy Buildings. This cannot be done without discussing the legislative and regulatory framework that applies for the building envelope, as solutions have to comply with regulations and standards, both national and international. In this line of approach an investigation of the practices and technical approaches best suited for Greece is being made, specifying their performance, possible drawbacks and approaches that are to be applied and the implementation of which is expected to contribute to the improvement of the buildings’ performance.

Furthermore, the constructional approaches and the effectiveness of both naturally and mechanically ventilated façades are discussed, along with their adaptation to the Greek building practices. The integration of ventilated façades with the building’s HVAC systems may offer advantages, especially in spring and fall when preheating the air may lead to reduced energy requirements. In the opposite direction, heat rejection may be a problem in summer, where alternative cooling techniques can provide a solution. Finally, integration of innovative design elements such as the use of different final coating materials on the façades, the use of phase-changing materials (PCMs) and the integration of photovoltaic systems are evaluated.
Optical analysis of an evacuated tube collector with built-in compound parabolic concentrator for process heat applications
Authors: Rosa Christodoulaki , Panagiotis Tsekouras , Vassiliki Drosou
Published: January 2020

To date, insufficient attention has been paid to the potential of renewable energy resources in industrial applications. Up to 21% of final energy demand and feedstock-use in the manufacturing industry sector could be of renewable origin by 2050. Process temperatures found in industrial processes range from low (T<100°C), medium (100°C < T < 250°C) to high (T > 250°C) temperatures. Whereas low temperature applications are already addressed by well-established collector technologies, the medium temperature applications are still in an early development stage. The aim of this study is to evaluate the optical performance of an Evacuated Tube Collector with Compound Parabolic Concentrator (ETC-CPC) used for medium temperature industrial process heat. To this end, an optical simulation model is developed in Tonatiuh ray-tracing software and is validated towards the theoretical fully developed curve. The parametric analysis performed investigates the impact of the truncation origin, the reflectivity of the CPC mirror and the absorber radius on the optical efficiency and the power production of the solar collector. It is found that the collector with the biggest truncation origin (0.025m) performs better under small Sun angles (0°-20°), but worse under greater Sun angles (40°-90°). This happens because the collector with the greatest truncation origin has the biggest mirror area and under small Sun deviations this leads to more gains and higher efficiency. The quality of the mirror plays an important role in the optical efficiency of the collector, but mainly for incident angles less than 20°. Moreover, increasing the radius of the absorber, the power production per aperture area is increased. The variation of the absorber radius shows that the radius of the base scenario compensates most of the optical errors but without being big enough to have excess heat loss. The results of this study are valuable for the design, simulation and performance analysis of ETC-CPC for delivering medium temperature heat.
New generation of theoretical models for the thermal response of geothermal heat exchangers
Authors: Hermanns Miguel
Published: January 2020

The efficient harnessing of geothermal energy for the heating and cooling of buildings requires extensive simulations to be carried out during the detailed design phase of a new building. These simulations, performed using semi-analytical models, serve to assess the thermal response of the geothermal heat exchanger during the building’s lifetime, that can easily excess 100 years. By using asymptotic expansion techniques, a new generation of theoretical models is being developed since 2011 that offer the flexibility and accuracy of the best performing models available nowadays, but at a fraction of their computational cost. These new models open the doors to yet untapped design and optimization possibilities.
Preliminary evaluation of operational results of RES systems integrated in students’ residences in Xanthi, Greece
Authors: Botsaris P N , Lymperopoulos K , Pechtelidis A
Published: January 2020

This paper discusses the techno-economic performance of installed renewable energy technologies in students’ residences of Democritus University of Thrace, in Kimmeria, Xanthi, North Greece. The students’ residences building complex includes eleven (11) buildings of total area of 14,819.09 m2 and accommodate 630 students. The RES technologies installed, include a hybrid solar thermal/biomass system for heating, cooling and domestic hot water of the students’ residences buildings and one amphitheater, a geothermal heat pumps system for heating and cooling of a restaurant, an autonomous PV system and one small vertical axis wind turbine. The above interventions were accomplished under “REUNI” project that was funded by EEA and Norway Grants program – GR03-Renewable Energy Technologies. The present study elaborates the operational results of almost two years of the RES technologies installed and highlights their techno-economic performance, through analysis of the collected operational data. The building complex of the students’ residences of DUTH in Kimmeria has managed to operate for its thermal and cooling energy demand with hundred per cent (100%) renewables throughout a year, resulting in significant energy costs and CO2 reduction. However, the operation and maintenance cost of the installed systems has been underestimated, resulting in increased number of days of unavailability. The results highlight the need to increase solar energy penetration, as well as the need for subsidy in order to compete with the fossil fuel technologies. The development of such systems that utilize renewable energy sources is considered as a priority for the increase of share of RES in the building sector. The experience from the operation of such system is valuable for the promotion of renewable energy in the built environment.
Which is the optimum option for parking in the city centre?
Authors: Alexandri Eleftheria , Lampropoulos Anastasios
Published: January 2020

Most contemporary Greek cities face the lack of adequate public space. This lack has a direct effect on parking space issues, turning cities’ open spaces into congested ones with parked cars. Although, according to Greek buildings’ regulations parking space must be provided within the building itself, especially in the county of Attica, where Athens, the capital, is located, the Law offers the possibility of exemption from this obligation in small building lots. Thus, in many cases, for small apartment buildings no parking space is provided within the building, forcing drivers to resort to either off-street parking or parking lots. Offstreet parking may cause more traffic jams, noise and loss of time, among other negative effects, while parking lots have turned into environmental catastrophes in many cases (Soup, 2017; Davis et al, 2010). On the other hand, the construction of a basement parking space is linked with high initial costs, while parking spaces on other floors deprive vital area from living spaces, let alone the embodied energy of constructing these spaces. In this paper Life Cycle Analysis and Multicriteria Analysis is made so as to compare which the most sustainable option is; the creation of underground and ground floor level parking spaces within a small apartment building, off-street parking or the creation of a parking lot to host these vehicles. The environmental, social and economic effects of these three cases are analysed, taking into consideration both their constructional and operational effects. A comparison is made between these three options, with criteria for environmental protection, social equity and economic growth, the three pillars of sustainability, selected from relevant indicators of sustainable development. Hierarchy of the three examined options (off-street, in a parking lot or within the building parking) is made with Multicriteria Analysis. Through this research conclusions are drawn on the policy that cities should follow, so as to face in the most sustainable way the demand for parking space and whether legislation should change in regards to the provision of parking spaces within small building lots.
The impact of building automation control systems as retrofitting measures on the energy efficiency of a typical Norwegian single-family house
Authors: Felius L C , Hamdy M , Hrynyszyn B D , Dessen F
Published: January 2020

In this study, the energy savings and cost-effectiveness of building automation measures in a retrofitting context are evaluated for a Norwegian single-family house. In addition, two methods for calculating savings from implementing building automation control systems (BACS) are compared: energy performance simulation and the BACS factor method proposed in EN 15232. Four retrofitting packages and four automation levels are combined to create 16 model versions. This study shows that BACS can increase energy savings and improve indoor comfort when implemented as a retrofitting measure. However, the relative impact on energy savings of building automation decreases when the delivered energy is lower. In addition, the impact of building automation on the energy savings is low compared to the effect of retrofitting the building envelope. When only BACS are implemented, savings up to 21% can be achieved, but when an integrated solution is implemented savings up to 60% can be achieved. Finally, some directions for future work are suggested.
Innovative financial schemes for buildings’ energy renovation
Authors: Polychroni Elpida , Androutsopoulos Andreas
Published: January 2020

Building energy renovation is a key issue to tackle the high energy consumption of the building stock. Many countries - especially the Mediterranean ones - have been strongly hit by the financial crisis of 2008 which has affected national economies and resulted in market uncertainty. On one hand, the financial resources are very limited and on the other hand, the energy efficiency policy of the European Union (EPBD recast and Energy Efficiency Directive) has become stricter with more ambitious goals in terms of energy efficiency and CO2 emissions, especially of the public building stock. Public authorities are not ready to implement them. Administrative and regulatory obstacles help to maintain an unsuitable environment for this kind of initiatives. The majority of public buildings can significantly improve their energy performance, but to mobilize these investments new financial instruments are necessary (such as Energy Performance Contracting-EPC) that will be negotiated with new market actors (Energy Services Companies-ESCOs).The current work tries to facilitate the decision to implement energy renovation measures in public buildings by the use of a tool. The Subsidy Evaluation Tool (SET) carries out an energy and financial evaluation of Energy Conservation Measures (ECMs) for buildings energy renovation and can be used for various types of public buildings. The main aim of the tool is to find innovative financing schemes that combine public resources with private investments and to create conditions for deep investments in energy efficiency actions for public buildings considered bankable by the market. The paper presents the structure of the tool, its layout, the parameters and formulas utilized, so as to provide with the most appropriate solution for energy retrofitting of buildings from a techno-economic point of view.
Mapping the deep renovation possibilities of European buildings
Authors: Androutsopoulos Andreas , Geissler Susanne , Charalambides Alexandros G. , Escudero Cristina Jareño , Kyriacou Orestis , Petran Horia
Published: January 2020

Energy efficiency is priority number one in the EU in the last two years and efforts to achieve it have been made in various ways: through regulations, guidelines, good practice results, education and training. The buildings sector still is the larger consumer of energy, so many policies and national energy strategies have prepared ambitious goals to significantly decrease the sector’s energy consumption. An important step for the implementation of these strategies is the detection of the potential to energy renovate the existing building stock. This is the objective of this study; to present the ENERFUND tool which displays the current energy performance of a group of buildings and pinpoints the energy renovation potential for the selected buildings. An extensive study to identify the expectations of the future users was carried out, which provided valuable feedback for the features of the tool. The tool utilizes data from publicly available Energy Performance Certificates in the form of an interactive web map and combines them with other geo-referenced data and general information to allow for a rating of deep renovation opportunities. The paper explains the various features of the tool, and presents typical examples of the tool use for targeted stakeholder interests.
High energy efficiency renovation options for a typical apartment. The case study of the SPITI project
Authors: Ampatzidis Petros , Serasidou Anna , Tsiaousi Aikaterini , Martinopoulos Georgios
Published: January 2020

The need for reduced energy consumption dictates a new way of thinking about the design, construction, and renovation of buildings. Proposing a repurposing retrofit of a top-floor apartment of a typical Greek multi-storey building, the International Hellenic University has qualified to the final stage of the Solar Decathlon Europe 2019 competition. The main aim of this study is to provide a solution towards the nearly (or net) zero energy buildings, paving the way for EU countries to achieve their energy conservation targets in the building sector. The solution includes the upgrade of the building envelope and its energy systems, the rearrangement of the interior space and the implementation of renewable energy sources. The assessment of the different retrofitting measures was carried out using EnergyPlus, while the System Advisory Model was employed to simulate the prototype’s solar systems. The final energy demand was reduced by approximately 88%, with the requirements for heating and cooling at 10.3 kWh/m2 and 14.1 kWh/m2, respectively. The electricity production from the photovoltaic system, namely 4,959 kWhe, can meet the annual electricity requirements leading to a 100% self-sufficient building.
Energy upgrading of existing collective housing with environmental and economic criteria: financial accessibility gap in cost-optimal energy retrofit of a ten-storey residential building in Athens, Greece.
Authors: Politis Alexandros , Andreou Eleni
Published: January 2020

The collective housing buildings developed during the construction boom of the 1970s and 1980s form the bulk of the contemporary urban fabric of Athens, Greece, the majority of which lack any intrinsic capacity of thermal protection. At the same time, unprecedented economic factors during the last decade depleted the disposable income of large parts of the population and threatened households’ ability to maintain conditions of thermal comfort. This original research focuses on a ten-storey collective housing unit of multiple owners, part of a larger 1972 complex, located in central Peristeri, one of the most densely populated areas at the west of the city-centre of Athens. Cost-optimality methodology was employed to compare the energy assessment of the current condition of the building and 15 energy retrofit scenarios consisting of four fundamental measures and all their possible combinations. This calculated the annual needs in primary energy and the total cost per square meter over a period of 15 years. A users’ questionnaire was employed as an additional methodological tool and a focus group of residents established their willingness to undergo a hypothetical energy retrofit of their residence and the amount of disposable income that each resident would be willing to dedicate to cover its costs. Findings demonstrate that although primary energy consumption could be reduced significantly from the current condition levels, self-funding is not sufficient to cover most of the energy retrofit scenarios’ initial investment costs, including the cost-optimal scenario, even if a common investment amount could be agreed among the multiple residents. This indicates the financial accessibility gap between sustainable retrofit of the existing collective housing stock and current household income.
Urban land cover mapping, using open satellite data. Case study of the municipality of Thessaloniki.
Authors: Tsolakidis Ioannis , Vafiadis Marios
Published: January 2020

The use of open satellite data has become a valuable tool for monitoring the urban environment due to high temporal, spectral and spatial resolution. Planners and stakeholders can rely on these data since they offer an alternative point of view of a very complex urban scenery. The processing of satellite images with the combined use of different types of data (statistical, in situ etc) can extract information for the present situation, in urban and suburban areas. This study use image data from the Sentinel satellite mission, in order to extract urban land cover characteristics in Thessaloniki city. The Sentinel mission started the image acquisition on 2014. The data set are freely available for downloading. The use of high resolution satellite images (e.g IKONOS) in urban studies, has been proved very useful all these years. On the other hand the use of a medium size spatial resolution satellite, as Sentinel-2, with 10m pixel size, is a very promising optical earth-observation satellite, which is tested in this study. Image processing techniques used to produce classified map of urban characteristics and land cover classes (built up areas, vegetation etc). The contribution of a radar image of Sentinel-1, in the classification process, is also tested. All the above processing is done with an automatic procedure, giving additional value to the proposed methodology. The final classified map will give planners a management tool for decision-making concerning the sustainable urban development and will be the basis for implementing hydrology studies, planning, land use change detection and other.