Local Temperature Control Research Articles

Analysis of Micro-Climate and Thermal Comfort in Campus Area (A Case Study: Unissula Campus, Kaligawe Semarang)

The dynamics of air temperature cause thermal comfort to be unstable in the context of an urban micro-climate. One of the places affected by the urban micro-climate is the campus of Unissula. It lies on the main transportation route of the north coast of Central Java. To create a comfortable space in the campus environment, a local scale air temperature control method is required, one of which is the provision of green open spaces (GOS). Scenarios for providing green open space based on micro-climate dynamics must be developed to create thermal comfort. This study aimed to identify and analyze the correlation between micro-climate and thermal comfort based on the existing parameters. The research methodology employed a rationalistic quantitative deductive approach with micro-climate and thermal comfort variables, as well as rationalistic descriptive analysis technique. According to the findings of this study, the comfort of Unissula campus meets the criteria for morning air temperature of 25.42°C, daytime 31.35 °C, evening 29.92 °C. The morning humidity is relatively 73.92%, the daytime is 51.50%, and the evening is 60.57%. The thermal comfort level is moderately partly comfortable.

The feasibility of jet fan-assisted ventilation for temperature control of heating belts on a downward-facing sphere in a scientific facility

To avoid the deformation of the large-scale scientific facility for neutrinos detection due to temperature changes, the heat generated during the top-down annealing of the inorganic glass panels needs to be released in time to maintain temperature control of 21±1°C in the built-up area. Due to the unique shape and the changing heating sources, a novel ventilation strategy that combines jet fans with general ventilation was proposed to satisfy the special environmental control requirement. A small-scale field experiment was conducted to obtain the CFD methods for simulation. Then, the feasibility of the jet fan-assisted ventilation system was discussed in terms of two thermal control zones based on the distance from the heat source. Besides, the effectiveness of the proposed ventilation design was compared with traditional general ventilation with air-conditioned air supplied from the hall ceiling and directly opposite the heating belt based on the temperature and velocity distribution. The results show that: the area outside the thermal control range under jet fan-induced ventilation was reduced by around 60%, and the maximum temperature fluctuated over time within 0.33°C. These results provide a preliminary insight into the use of jet fan-assisted ductless ventilation to achieve precision local temperature control in a large space.

Post‐extrusion process for the robust preparation of highly uniform multiphase polymeric 3D printing filaments

AbstractFused filament fabrication 3D printing demands the preparation of polymeric filaments of highly uniform dimensions in order to achieve the best possible mechanical performance. This stringent requirement is a challenging task and becomes even more difficult when multiphase hybrid polymers are used. In this work, a post‐extrusion setup is presented, allowing for the preparation of immiscible quaternary polymeric blend filaments of highly stable dimensions. The polymer blend used is bio‐based and is comprised of poly(L‐lactide), poly(ethylene oxide), poly(ether‐b‐amide), and polyamide‐11. The setup is connected to an extruder die. By incorporating a precisely localized temperature control over a pathway of 66 mm, the extrudate melt is initially transformed into a stable semisolid state. Forced convection cooling, imposed at a distance of 4–5 mm from the last static cooling zone, allows thereafter the complete solidification of the profile. Filaments with a uniform diameter of 1.75 and 2.85 mm are manufactured. The developed approach can be used to manufacture, otherwise non‐processable, complex quaternary polymer blend filaments with a highly controlled diameter in the range of 0.1–4.5 mm with no restriction regarding the filament length. The produced filaments were used to 3D print dogbone samples with very high elongation at break.

Study of solar radiation on an all-movable radio telescope

To grasp the effect of nonuniform temperature field, the effects of a nonuniform sunshine temperature field on a large, all-movable radio telescope were analyzed in this study. Based on the overall parameters of a radio telescope model, first, several specific steps of the ray-casting algorithm were introduced for calculating sunlight shadows on radio telescopes, and then a special program was developed for simulating sunlight and shadows on radio telescopes. Second, the periodic air temperature, heat radiation, and heat conduction were computed every half hour under a cloudless sky on a summer day, i.e., the worst-case climate conditions. The transient structural temperatures were then analyzed over a period of several days of sunshine with a rational initial structural-temperature distribution until the whole set of structural temperatures converged to the results obtained the day before. As a result, the temporal and spatial characteristics of the temperature distribution for the radio telescope were statistically investigated. Furthermore, the phenomenon called the solar cooker effect was found to exist in such a Cassegrain reflector system. The variations in the solar cooker effect over time and its spatial distributions in the secondary reflector were observed to elucidate the mechanism of the effect. The results presented here provide some references for the future operation, sensor distribution, and local temperature control of radio telescopes.

Imitation model of heat flows distribution in building heating control system

Implementation of automatic heating control systems allows us to reduce heat consumption by 10% in residential areas and 40% in office and educational buildings. Currently, there are heating control systems, however, they are applied only to a single-level two-pipe heating system. Development of an imitation model of heat flows redistribution is necessary to synthesize the system of interconnected dynamic heating control of a building. Unlike existing solutions, this research work considers the problem of unbalanced heat flow in a multi-level hierarchical heating system. Calculation of convective heat transfer in the room assumes that the air temperature at any given time is the same throughout the entire room. When we determine heat transfer through walling, it is assumed that the walling or its part has the same temperature of the planes perpendicular to the direction of air flow. In this case, the heat transfer process is described by a one-dimensional heat transfer equation. The developed model of heating control systems allows us to connect the automatic control modules, change control algorithms at the compilation stage and in the system state during the simulation process. In comparison with possible analogue models based on AnyLogic or ANSYS modeling systems, the presented model is the model of controlled object. It is easily combined with models of automatic control units and considers the problem of imbalance of heat flows. An example of the functional scheme of the local temperature control system around one battery is considered. Implementation of developed imitation model makes it possible to ensure a new level of quality control of technological processes of production and consumption of power energy resources by using modern information technologies and synthesizing a system of interconnected dynamic heating control. Possibilities of such modeling are focused on development of the uninterrupted and high-quality heat supply system, maintaining energy-efficient operating modes, as well as actual economic effect. The model under consideration allows us to simulate redistribution of heat flows in different operating modes of the heating system.

All-fiber narrow-bandwidth rectangular Optical filter with reconfigurable bandwidth and tunable center wavelength.

In this manuscript, a novel narrow-bandwidth rectangular optical filter based on multi-phase-shifted fiber Bragg grating (MPSFBG) is proposed. Using the local temperature control technology, the precise controllable phase shifts are introduced at different positions of the fiber Bragg grating (FBG). Therefore, the bandwidth of the MPSFBG-based filter with good shape factor can be reconfigured from 70 MHz to 1050 MHz by flexibly controlling the numbers and the positions of the phase shifts introduced in the MPSFBG. In addition, the center wavelength of the MPSFBG-based filter can be tuned through controlling the MPSFBG's environment temperature, and the tuning range of 22 GHz is realized. This is one of the best results for the narrow-bandwidth rectangular optical tunable filter with reconfigurable bandwidth. It can be widely used in the processing of reconfigurable signals in the optical communication networks and microwave photonics.

The heat flow coupling effect of laser-assisted magnetorheological polishing

During the magnetorheological polishing process of concave workpieces, the magnetorheological fluid tends to accumulate at the entrance of the polishing zone, resulting in a decrease in the polishing efficiency and quality. To solve this problem, in this paper, laser-assisted magnetorheological polishing technology was proposed. Based on the theory of fluid mechanics and heat transfer, a three-dimensional temperature field distribution model of the spherical polishing film was established to achieve local temperature control at the entrance of the polishing zone. Then, the functional relationship between the viscosity of the magnetorheological fluid and the temperature was obtained experimentally. On this basis, the shear force and hydrodynamic pressure models of the polishing zone were established, which reveal that the heat flow coupling effect can increase temperature at the inlet of the polishing zone and reduce the viscosity of the local magnetorheological fluid, thereby reducing the shear stress in the polishing zone. The results show that when the laser power is 3 W and the magnetorheological fluid flow rate is 6 ml/s, the viscosity of the magnetorheological fluid at the entrance can be effectively reduced, and the shear force in the polishing zone decreases slightly.

Plasmonic Layer as a Localized Temperature Control Element for Surface Plasmonic Resonance-Based Sensors.

Surface plasmon resonance (SPR) sensing is a well-established high-sensitivity, label-free and real-time detection technique for biomolecular interaction study. Its primary working principle consists of the measurement of the optical refractive index of the medium that is in close vicinity of the sensor surface. Bio-functionalization techniques allow biomolecular events to be located in such a way. Since optical refractive indices of any medium varies with the temperature, the place where the measurement takes place shall be within a temperature-controlled environment in order to ensure any temperature fluctuation is interpreted as a biomolecular event. Since the SPR measurement probes the sensed medium within the penetration depth of the plasmonic wave, which is less or in the order of 1 µm, we propose to use the metallic film constituting the detection surface as a localized heater aiming at controlling finely and quickly the temperature of the sensed medium. The Joule heating principle is then used and the modeling of the heater is reported as well as its validation by thermal IR imaging. Using water as a demonstration medium, SPR measurement results at different temperatures are successfully compared to the theoretical optical refractive index of water versus temperature.

Modeling and Simulation of an Invasive Mild Hypothermic Blood Cooling System

Nowadays, mild hypothermia is widely used in the fields of post-cardiac arrest resuscitation, stroke, cerebral hemorrhage, large-scale cerebral infarction, and craniocerebral injury. In this paper, a locally mixed sub-low temperature device is designed, and the cold and hot water mixing experiment is used to simulate the human blood transfer process. To set a foundation for the optimization of the heat transfer system, the static characteristics are analyzed by building the mathematic model and setting up the experimental station. In addition, the affection of several key structure parameters is researched. Through experimental and simulation studies, it can be concluded that, firstly, the mathematical model proved to be effective. Secondly, the results of simulation experiments show that 14.52 °C refrigeration can reduce the original temperature of 33.42 °C to 32.02 °C, and the temperature of refrigerated blood rises to 18.64 °C, and the average error is about 0.3 °C. Thirdly, as the thermal conductivity of the vascular sheath increases, the efficiency of the heat exchange system also increases significantly. Finally, as the input cold blood flow rate increases, the mass increases and the temperature of the mixed blood temperature decreases. It provides a research basis for subsequent research on local fixed-point sub-low temperature control technology.

High-Precision Multiphase Shifts Generation and Filter Fabrication Based on Grating Local Temperature Control

High-Precision Multiphase Shifts Generation and Filter Fabrication Based on Grating Local Temperature Control

Sural Nerve Perfusion in Mice.

Peripheral nerve function is metabolically demanding and nerve energy failure has been implicated in the onset and development of diabetic peripheral neuropathy and neuropathic pain conditions. Distal peripheral nerve oxygen supply relies on the distribution of red blood cells (RBCs) in just a few, nearby capillary-sized vessels and is therefore technically challenging to characterize. We developed an approach to characterize distal sural nerve hemodynamics in anesthetized, adult male mice using in vivo two-photon laser scanning microscopy. Our results show that RBC velocities in mouse sural nerve vessels are higher than those previously measured in mouse brain, and are sensitive to hindlimb temperatures. Nerve blood flow, measured as RBC flux, however, was similar to that of mouse brain and unaffected by local temperature. Power spectral density analysis of fluctuations in RBC velocities over short time intervals suggest that the technique is sufficiently sensitive and robust to detect subtle flow oscillations over time scales from 0.1 to tens of seconds. We conclude that in vivo two-photon laser scanning microscopy provides a suitable approach to study peripheral nerve hemodynamics in mice, and that local temperature control is important during such measurements.

Recent Insights into the Potential of Magnetic Metal Nanostructures as Magnetic Hyperthermia Agents

The advancements in magnetic nanoparticle mediated hyperthermia give so many optimistic and fruitful results that make it a promising and complementary approach for the existing treatment modalities of cancer. This thermotherapy is gaining wide acceptance among the medical community compared to the conventional treatment methods. The former provides a local heat generation in the malignant tumor cells and remains non-invasive to the adjacent healthy cells. The increased heating efficiency of magnetic nanoparticles and the control of local therapeutic temperature are the main challenges of hyperthermia. Superparamagnetic Iron Oxide nanoparticles have been intensively studied and dominating in magnetic hyperthermia. Recently many researchers successfully demonstrated high heating efficiency and biocompatibility of a wide variety of magnetic metal nanoparticles and proposed as the most promising alternative for traditional iron oxides, which opens up a new avenue for magnetic metal nanoparticles in magnetic hyperthermia. The review presents the recent advancements that occurred in the field of metal nanoparticle mediated magnetic hyperthermia. The theory underlying heat generation, synthesis methods, biofunctionalization, Specific Absorption Rate studies, challenges and future perspectives of magnetic metal nanoparticles are presented. This will inspire more in-depth research and advance practical applications of metal nanoparticles in magnetic hyperthermia.

Dy-DTPA as supersensitive shifting and relaxational probe for NMR/MRI control of local temperature

The article develops an approach in which paramagnetic lanthanide complexes are considered and studied as NMR / MRI relaxational and shifting probes for determining local temperature and prospective diagnostics. A detailed NMR study of the paramagnetic properties of Na2[Dy(DTPA)(H2O)] (I) complex is an example of the application of this approach. The substantial temperature dependence of the transverse relaxation on the ligand nuclei at high magnetic fields is due to the Curie spin contribution to the paramagnetic relaxation rate enhancement. A significant temperature dependence of relaxivity r2 was experimentally detected. The activation free energy of the racemization ΔG≠(298) in I is found to be 50 kJ mol−1. The coordination compound I can also serve as the most sensitive 1H NMR relaxational and shifting lanthanide paramagnetic probe for in situ temperature control in liquid medium.

Selective Brain Hypothermia in Acute Ischemic Stroke: Reperfusion Without Reperfusion Injury.

In acute ischemic stroke, early recanalization of the occluded artery is crucial for best outcome to be achieved. Recanalization aims at restoring blood flow to the ischemic tissue (reperfusion) and is achieved with pharmacological thrombolytic drugs, endovascular thrombectomy (EVT) devices, or both. The introduction of modern endovascular devices has led to tremendous anatomical and clinical success with rates of substantial reperfusion exceeding 80% and proven clinical benefit in patients with anterior circulation large vessel occlusions (LVOs). However, not every successful reperfusion procedure leads to the desired clinical outcome. In fact, the rate of non-disabled outcome at 3 months with current EVT treatment is ~1 out of 4. A constraint upon better outcomes is that reperfusion, though resolving ischemic stress, may not restore the anatomic structures and metabolic functions of ischemic tissue to their baseline states. In fact, ischemia triggers a complex cascade of destructive mechanisms that can sometimes be exacerbated rather than alleviated by reperfusion therapy. Such reperfusion injury may cause infarct progression, intracranial hemorrhage, and unfavorable outcome. Therapeutic hypothermia has been shown to have a favorable impact on the molecular elaboration of ischemic injury, but systemic hypothermia is limited by slow speed of attaining target temperatures and clinical complications. A novel approach is endovascular delivery of hypothermia to cool the affected brain tissue selectively and rapidly with tight local temperature control, features not available with systemic hypothermia devices. In this perspective article, we discuss the possible benefits of adjunctive selective endovascular brain hypothermia during interventional stroke treatment.

Local temperature control improves the accuracy of cardiac output estimation using lung-to-finger circulation time after breath holding.

As timely measurement of the cardiac index (CI) is one of the key elements in heart failure management, a noninvasive, simple, and inexpensive method of estimating CI is keenly needed. We attempted to develop a new device that can estimate CI from the data of lung‐to‐finger circulation time (LFCT) obtained after a brief breath hold in the awake state. First, we attempted to estimate CI from the LFCT value by utilizing the correlation between 1/LFCT and CI estimated with MRI. Although we could obtain LFCT from 45 of 53 patients with cardiovascular diseases, we could not find the anticipated relation between 1/LFCT and CI. However, we realized that when we adopted only LFCT from patients with a finger temperature of ≥31°C, we could obtain a consistent and clear correlation with CI (correlation coefficient, r = .81). Thus, we next measured LFCT before and after warming the forearm. We found that LFCT decreased after the local temperature increased (from 27.5 ± 13.6 to 18.4 ± 5.3 s, p < 0.01). The correlation between the inverse of LFCT and CI improved after warming (1/LFCT vs. CI, from r = .69 to r = .82). The final Bland–Altman analysis between the measured and estimated CI values revealed that the bias and precision were −0.05 and 0.37 L min−1 m−2, respectively, and the percentage error was 34.3%. This study clarified that estimating CI using a simple measurement of LFCT is feasible in most patients and a low fingertip temperature strongly affects the CI‐1/LFCT relationship, causing an error that can be corrected by proper local warming.

Evaluation of the Response Characteristics of On-Chip Gel Actuators for Various Single Cell Manipulations

On-chip gel actuators are potential candidates for single cell manipulation because they can realize low-invasive manipulation of various cells. We propose an on-chip gel actuator driven by light irradiation. By patterning the gel actuator with light absorber, we can control the temperature of the actuator and drive it. The proposed drive method can realize highly localized temperature control of the gel actuator and can be applied to mass integration of on-chip gel actuators. In this study, we evaluate the heat conduction of the actuator during driving and its response characteristics as a function of various design parameters. We theoretically and experimentally evaluate the response characteristics and confirm that the response characteristics can be changed by altering the size of the light absorber. Furthermore, we show some examples of cell manipulation including trapping, transport, and sorting with various sizes of light absorber. Finally, we show proof of concept for the application of the proposed drive method for massive integration of on-chip gel actuators.

Building temperature regulation in a multi-zone HVAC system using distributed adaptive control

During recent years there have been considerable research efforts on improving energy efficiency of buildings. Since Heating, Ventilation and Air-Conditioning (HVAC) systems are responsible for a big part of energy consumption, developing efficient HVAC control systems is crucial. In most of the developed approaches, precise knowledge of system parameters and/or adequate historical data is required. However, these approaches may not perform as well in the presence of dynamic parameter changes due to human activity, material degradation, and wear and tear, or disturbances and other operational uncertainties due to occupancy, solar gains, electrical equipment, and weather conditions. In this paper, we consider buildings with several climate zones and propose a distributed adaptive control scheme for a multi-zone HVAC system which can effectively regulate zone temperature by applying on-line learning and assuming exchange of information between neighboring zones. The controller of each zone achieves the local objective of controlling zone temperature by compensating for the effects of neighboring zones as well as for possible changes in the parameters of the system. Despite the exchange of information, each local controller does not know how the control actions and temperature of a neighboring zone affect the temperature of its own zone. For this reason, each local controller is estimating the parameters of the interconnections in real time and uses them together with the exchanged information to provide a more accurate local zone temperature control. The proposed method is illustrated using an example of temperature control in a six-zone building as well as a large school building, which are implemented in a Building Controls Virtual Test Bed (BCVTB) environment using EnergyPlus and MATLAB/Simulink.

Dy-DTPA as Supersensitive Shifting and Relaxational Probe for NMR / MRI Control of Local Temperature

Dy-DTPA as Supersensitive Shifting and Relaxational Probe for NMR / MRI Control of Local Temperature

Coupled Plasmon Modes in 2D Gold Nanoparticle Clusters and Their Effect on Local Temperature Control

Assemblies of closely separated gold nanoparticles exhibit a strong collective plasmonic response due to coupling of the plasmon modes of the individual nanostructures. In the context of self-assembly of nanoparticles, closed packed 2D clusters of spherical nanoparticles present an important composite system that promises numerous applications. The present study probes the collective plasmonic characteristics and resulting photothermal behavior of closed packed 2D Au nanoparticle clusters in order to delineate the effects of cluster size, inter-particle distance and particle size. Smaller nanoparticles (20 nm and 40 nm in diameter) that exhibit low individual scattering and high absorption were considered for their relevance to photothermal applications. In contrast to typical literature studies, the present study compares the optical response of clusters of different sizes ranging from a single nanoparticle up to large assemblies of 61 nanoparticles. Increasing the cluster size induces significant changes to the spectral position and opto-physical characteristics. Based on the model outcome, an optimal cluster size for maximum absorption per nanoparticle is also determined for enhanced photothermal effects. The effect of particle size and inter-particle distance is investigated in order to elucidate the nature of interaction in terms of near-field and far-field coupling. The photothermal effect resulting from absorption is compared for different cluster sizes and inter-particle distances considering a homogeneous water medium. A strong dependence of the steady state temperature of the nanoparticles on the cluster size, particle position in the cluster, incident light polarization and inter-particle distance provides new physical insight in local temperature control of plasmonic nanostructures.

Turning Up the Heat: Local Temperature Control During in vivo Imaging of Immune Cells.

Intravital imaging is an invaluable tool for studying the expanding range of immune cell functions. Only in vivo can the complex and dynamic behavior of leukocytes and their interactions with their natural microenvironment be observed and quantified. While the capabilities of high-speed, high-resolution confocal and multiphoton microscopes are well-documented and steadily improving, other crucial hardware required for intravital imaging is often developed in-house and less commonly published in detail. In this report, we describe a low-cost, multipurpose, and tissue-stabilizing in vivo imaging platform that enables sensing and regulation of local tissue temperature. The effect of tissue temperature on local blood flow and leukocyte migration is demonstrated in muscle and skin. Two different models of vacuum windows are described in this report, however, the design of the vacuum window can easily be adapted to fit different organs and tissues.