Distributions of moisture content and temperature within cedar specimens under steady heating were measured with thermocouples and moisture sensors developed in ref.10), and compared with heat and water transfer analysis. Increasing of moisture content caused by heat ant water transfer was measured in experiments, and enable to be represented by analysis.
Moisture content as well as temperature affects fire resistant performance of wooden member during fire. In particular, charring rate become slow because of heat capacity of water, and mechanical properties decrease significantly even under 100℃ at high moisture content. In most literatures, fire resistant performance had been simply predicted with only temperature because of lack of a measurement system of local moisture content.
Cedar specimens whose thickness was 45mm located thermocouples and developed moisture content sensors10) were heated from flat grain by cone calorie meter. Located moisture content measurement systems calculated moisture content with electric resistance between two electrodes for each measurement point in specimens, and measurement range is most effective at 10~30 % moisture content. Each three Specimens were heated 60 minutes by 4.5 kW/m2, and 30 minutes by 20 kW/m2. Local moisture content increased gradually to 27.8% in maximum even temperature was under 100℃ by 4.5 kW/m2 heating, increased temporarily to over 30% in maximum by 20 kW/m2 heating. Increasing of moisture content was caused under 100℃, thereby attributed to water evaporation in area at about 100℃, transfer, and re-condensation. Time variations of moisture content was differed from each specimen even at the same heat strength.
Temperature, moisture content, total pressure and vapor pressure were coupled and calculated by Crank-Nicolson method in the model for heat and water transfer. Changes of moisture content is caused by adsorption/desorption rate defined explicitly. Specifically, water evaporation in higher temperature area, vapor transfer, increasing of vapor pressure in lower temperature area, increasing of relative humidity, increasing of equilibrium moisture content and increasing of adsorption rate cause increasing of moisture content.
The agreement for temperature between experiments and calculation results was good; however, improvement of accuracy of the moisture content measurement system and investigation of influence of grains of wood were needed because quantitively comparison was difficult by difference of time variation of moisture content at the same heat strength. Closer to unheated surface, difference between experiments and calculation results of moisture content became larger. In addition, modeling of the process of char oxidation and mass decrease and improvement of adsorption- isotherm will be necessary because temperature increasing was a bit slower and the maximum value of moisture content in experiments was bigger than maximum values of adsorption-isotherm.
In the future, two-dimensional analysis and prediction for distribution of temperature and moisture content within a full-scale member exposed to unsteady heating is required. Furthermore, prediction and evaluation of influences of heat and water transfer for mechanical properties is important.
In this study, a method for predicting the unexposed surface temperature of triple-layer wall is proposed by using "inclusive thermal conductivity" which considers transfer of heat and moisture, and influence of occurring cracks and contained water in materials. In our previous studies, the unexposed surface temperature was predicted by using the inclusive thermal conductivity for single- and double-layer wall. In each case, more accurate temperature history was also obtained by this numerical calculation. The proposed method will enable the estimation of thermal conductivities of materials that are difficult to assess using conventional technologies. Fire-resistance tests were conducted on specimens with fiber-reinforced cement siding, insulation, and gypsum boards overlaid. Fire-resistance tests were conducted based on ISO834. Inclusive thermal conductivities are estimated based on the results of temperature measurements from fire-resistance tests.
The inclusive thermal conductivities are calculated by using the finite differential method. The inclusive thermal conductivities of fiber-reinforced cement siding and gypsum board that were estimated in the study on the double-layer wall were examined whether it is possible to work well enough on the prediction for triple-layer. The inclusive thermal conductivity of the insulation was estimated using the inclusive thermal conductivities for the double-layer which were estimated in our previous study. On the estimation of the inclusive thermal conductivity, the calculated internal temperatures of the materials, temperature between materials, and unexposed surface temperature were compared with the experimental results. Additionally, on estimation of inclusive thermal conductivities the influence of the moisture behavior and cracks in the materials are considered. Since the inclusive thermal conductivities have some peaks and/or dips at various temperatures, they are approximated to polynomial approximation for each temperature region.
In order to estimate that unexposed surface temperature of similar triple-layer specimen whose thickness of gypsum board layer is decreasing, the number of inclusive thermal conductivities are reduced. In the case of estimating the specimen thickness whose thickness is changed, the inclusive thermal conductivities of predictive calculations were performed by removing layers of the same thickness as the divided layer. The calculations using this inclusive thermal conductivity sufficiently captured the temperature history. The prediction accuracy of numerical analysis using the inclusive thermal conductivity was found to be practically sufficient. As a result, the inclusive thermal conductivities estimated for double-layer can apply the prediction for triple-layer well enough.
The purpose of this study was to investigate whether skin dryness sensation is based on the actual skin condition, for example, hydration level in stratum corneum.
Subjective experiment had been carried out with the cooperation of sixteen young males and females.
In experimental procedure, after subjects had been acclimated to ambient environment in test chamber room for over thirty minutes, they answered to questionnaire for evaluating ambient humidity condition and own body dryness condition. In addition, hydration level in stratum corneum, transepidermal water loss, sebum level and skin surface temperature on cheek were measured after questionnaire had been finished. In this paper, the analysis was performed targeting under the condition that subjects did not perceived sweating. The results and findings are listed below.
1) It was found that there is a significant partial correlation coefficient between hydration level in stratum corneum and cheek dryness sensation, if the sebum level was the same.
2) In male subjects, a significant correlation was observed between the hydration level in stratum corneum and cheek dryness sensation, regardless of sebum level. And although not significant, their hydration level in the stratum corneum showed a weak correlation with actual environmental humidity.
3) In female subjects, the dryness sensation on cheek was observed to have a significant positive correlation not with hydration level in stratum corneum but with sebum level. In addition, it was shown that the sebum level is an explanatory variable that can predict the dryness sensation on cheek well. Moreover, there was no significant correlation coefficient between sebum level and actual environmental humidity.
4) Cheek dryness sensation by female subjects was also strongly correlated with humidity sensation that is an evaluation index for environmental humidity. However, it was observed that there is no significant correlation between female humidity sensation and actual environmental humidity. Furthermore, humidity acceptability to environment showed a covariant relationship with sebum level.
From the above, the smaller the hydration level in stratum corneum, the more the cheek dryness sensation tends to be evaluated as being "dry", under the stipulation of constant sebum level. However, female dryness sensation on cheek may depend on rather the sebum level than the hydration level in stratum corneum. As a result, the environment in which female subjects claim "I feel dry on my cheeks and the ambient air, so it is unacceptable" was not always lower humidity.
On the other hand, in this paper, there is not enough consideration about individual differences in absolute values of skin condition. Because no experiments were conducted to expose and acclimate all subjects to the same temperature and humidity conditions. In addition, there is not enough data available to consider and explain the reason of gender differences. Therefore, further study on these issues is a topic for the future.
In this study, in order to avoid restricting the human body movement, non-contact, non-invasive and non-restrained mat type body motion sensors that measure fluctuations of a pressure loaded on the mat by the human body were used to determine heart rate, respiratory rate, and body motion. The indoor air and wall surface temperatures, humidity, carbon dioxide concentration, illuminance, and airflow speed were measured in the room as environmental factors during sleep. A questionnaire survey was conducted to clarify the sleep quality that the examinee felt just after sleep by OSA sleep inventory MA version (OSA). The obtained heart rate data is numerically analyzed to calculate Heart rate variability (HRV). HRV is the temporal fluctuation of heart rate (HR) and has been often used in the study of autonomic nerve activity of human body. In this analysis, HRV is calculated by an original method with reference to the European guidelines for calculating HRV using ECG data.
As subjective evaluation of sleep, Structural Equation Modeling (SEM) by exploratory factor analysis was performed between Environmental factors, the body motion and the HRV (vital factors), and results from OSA. This analysis was used Environmental factors and vital factors classified by the entire sleep time, period of 90 minutes after the start of sleep (first90), and period of 90 minutes before getting up (last90).
Fig. 5, 6, 7, 8, 9 shows result of SEM that adopted fit measures by discrepancy, SRMR, GFI and CFI. Fig. 5 suggest that OSA’s “Sleepiness or rising” might be affected by the average body motion count and heart rate (HR) at first90. Fig. 6 suggest that OSA’s “Initiation and maintenance of sleep” might be affected by the average body motion count at first90 and the average carbon dioxide concentration at the entire sleep time. Fig. 7 suggest that OSA’s “Frequent dreaming” might be affected by the average LF/HF at the entire sleep time and the standard deviation HR at last90. Fig. 8 suggest that OSA’s “Refreshing” might be affected by the average body motion count, HR, and wall radiation temperature at first90. Fig. 9 suggest that OSA’s “Sleep length” might be affected by the average body motion count at first90 and the average carbon dioxide concentration at the entire sleep time. These means first90 is most important for sleep quality. And that the average of the HR at first90 might be affected by the average of the wall radiation temperature during that period. And more that the standard deviation of HR at last90 might be affected by the average and the standard deviation of the carbon dioxide concentration and the average of the wall radiation temperature during that period.
Among the environmental factors, carbon dioxide concentration and wall radiation temperature were the factors that most affected subjective feeling of sleep.
These models suggested that there were more factors affecting the results. On the other hand it was suggested that optimizing the indoor environment could improve the subjective feeling of sleep.
We performed a post occupancy evaluation in a school building in which transparent glass was installed from floor to ceiling in a side corridor. The glass allowed students with hearing impairment to see each other from both the side corridor and an external passage placed alongside the corridor. We performed an experiment to determine how the psychological quantities of students with hearing impairment vary when an imitation wall is installed as the side corridor skin to decrease the glass area and narrow the view. We obtained the following results.
1) The mean assessment of the thermal environment in the side corridor reported by students and faculty was that it was hotter in summer and colder in winter than usual, except for the first floor, which receives no direct sunlight. The fifth and sixth floors, which offer almost no shade, were more intolerable than other floors because of their large windows and consequent heat in summer. The mean value students reported on a five-level rating scale for window size on each floor was “just the right size” when viewed from both the side corridor and external passage, and there was little difference among floors. Overall, 11% of students and 32% of faculty members said the window “should be slightly smaller” or “should be smaller, ” respectively.
2) The mean assessment varies depending on wall type, even with the same glass area. The mean assessment tended to become more positive when we used a wainscot and hanging wall or wall with slits, and more negative when we used a hanging wall.
Based on the experimental result, we examined whether dissatisfaction and intolerance differed significantly between a 100% glass area ratio and each glass area ratio in each wall type. We used a chi‐square test with a significance level of 1%. No significant differences were proved when the glass area ratio was 83% and greater with a hanging wall, 67% and greater with wainscot, 50% and greater for a wainscot and hanging wall, and 67% and greater for a wall with slits. Although we cannot say that statistically there were no significant differences between a glass area ratio of 100% and the cases with these glass area ratios, the above result shows us how to decrease the glass area ratio below 100% without considerably increasing dissatisfaction and intolerance, except for the case of 67% for wainscot in which the dissatisfaction and intolerance rates are higher than the other cases.
LED lighting technology has been seeing increasing use in sports facilities. LED lighting has characteristics such as a small light-emitting area and high directionality, which may cause glare. The JIS Recommendation for sports lighting provides recommended values for illuminance and uniformity as well as glare for outdoor sports facilities. However, it does not determine the recommended value for glare in gymnasiums. The purpose of this study is to reduce glare from luminaires in visual field during sports competition in gymnasiums. In this paper, measurements of light environment were carried out in eleven gymnasiums (six with LED lighting and five with HID lighting).
In order to evaluate glare felt during sports, the luminance distribution of players’ visual fields and that of the light-emitting area of the luminaires as well as illuminance distribution were measured. Measurements were conducted assuming a badminton game in which players may look at luminaires directly. The illuminance distribution was measured based on JIS method. The luminance distribution was measured by digital cameras. To measure the luminance distribution of players’ visual fields, a wide-angle lens was used, while a narrow-angle lens was used for the measurement of the luminance distribution within a luminaire. Since the line of sight of a player always moves, the luminance distribution of visual field was measured to cover various elevation angles at a measurement point on the court. Since the luminance distribution of a luminaire differs depending on the relative position between the luminaire and an observer, the luminance distribution of the luminaire was measured from different observers’ positions.
In the results of measured illuminance distribution, four of the eleven gymnasiums had higher than 750lx of average illuminance (JIS classification is I), three of the eleven gymnasiums had higher than 500lx and lower than 750lx (JIS classification is II), and the final four of the eleven gymnasiums had lower than 500lx (JIS classification III).
Since the maximum luminance value of the visual field cannot be measured precisely, measured luminance distribution was evaluated by percentile value in this study. In the result of measured luminance of the visual field with a 90-degree elevation angle, the 0.1% tile values of the luminance were higher than 40,000 cd/m2 in 68% of the gymnasiums. Analysis of 0.1% tile, 0.5% tile and 1% tile values of luminance in the visual field showed that the luminance in the visual field was increased as the elevation angle increased. Analysis of 0.1% tile, 0.5% tile, 1% and 50% tile values of luminance in the visual field showed that the luminance in the visual field was increased as the facility grade classification increased.
Since it is difficult to determine the light-emitting area in luminaires, the area with higher than 1,000 cd/m2 of luminance is considered a light-emitting area. In larger than 60-degree elevation angles, the average luminance of light-emitting area (area with higher than 1,000 cd/m2 of luminance) was higher than 20,000 cd/m2 in all gymnasiums. A significant difference in average luminance of the light-emitting area between the elevation angles was found. At all the elevation angles and all facility grade classifications by JIS, the average luminance of the light-emitting area in the gymnasium with LED lighting was significantly higher than that of the light-emitting area in the gymnasium with HID lighting.
Using the heat load calculation program (LESCOM) developed by the authors, we conducted a thermal load simulation using the weather data of the recent Japan Meteorological Agency in Tokyo for 60 years, captured the annual heating and cooling load, the instantaneous peak load and predicted the heating and cooling load in the near future.
In addition, we examined the correspondence in the solar shading control of the opening to decrease the cooling load and the following conclusions were obtained.
(1) The annual cooling load in the detached house in Tokyo has been decreasing from 1960 to 1969, and has been on an increasing trend since 1972. The most recent building standard level estimated increase is 0.067GJ/year.
(2) The annual heating load has decreased since 1960. It tends to be small. The estimated decrease in the most recent building standard level is 0.096GJ/year.
(3) The instantaneous cooling load in Tokyo is on a declining trend from 1960 to 1969, It has been on an increasing trend since 1972.The estimate of the most recent is 0.227kW/year.
(4) The annual cooling load of the window is decreasing from 1960 to 1969, and has been on an increasing trend since 1972. The estimated increase in the most recent is 0.014kW/year.
(5) The annual cooling load of the outside wall incorporation is decreasing from 1960 to 1969, and has been increasing since 1972. Similarly the estimated increase is 0.005kW/year.
(6) The instantaneous heating load in Tokyo has been decreasing since 1960 to the present day. The estimated decrease in the most recent is 0.023kW/year.
(7) The annual heating load of the outside wall has been decreasing since 1960 to the present day. The estimated decrease in the most recent is 0.023kW/year.
(8) As a method for the cooling load to increase the housing, the thermal load minimum control is the most effective in the blind control. Compared to +45-degree fixed blind in 2019, the minimum thermal load control can reduce the cooling load per year of 0.017GJ.
(9) The minimum thermal load control by the opening and closing control of the curtain can reduce the cooling load per year by 0.031GJ compared to the fixed lace curtain in 2019.
Pedestrians can work comfortably without worrying about UV rays or rain in semi-outdoor spaces inside shopping arcades in urban commercial areas, because wind and rain and solar radiation are blocked by buildings on both sides and covered top with canopy of shopping arcades. On the other hand, it is difficult for wind to pass through the arcades and heat is easily accumulate inside the arcades. So, it is important to consider the improvement of thermal environment in the arcades in summer.
Kumamoto city has been seriously affected by urban heat island phenomena especially in summer same as other major regional urban centers in Japan. In this study, for the improvement of resident’s living environment, three shopping arcades and adjacent city blocks in Kumamoto city center were targeted, and the influence of city blocks’ spatial structure including buildings, parking lots, green spaces etc. upon summer thermal environment inside arcades was evaluated from field measurements and numerical simulations.
The results showed that the spatial structure of both arcades and adjacent city blocks had affected the thermal environment inside arcades. In many time sections, air temperature in the arcades had been lower than in the street with trees. From this it was confirmed that the effect of solar shading by the canopy of the arcades and adjacent city blocks, and the effect of cold air from an adjacent open store. At the same time, it was also confirmed that the importance of the shape of the building and the open space in the adjacent city blocks for improving the heat radiation environment and airflow environment in the arcades.
Furthermore, the subjective reporting survey had conducted upon pedestrians in arcades. As the answers had matched with SET* at living height (1.5m from the ground) in the arcades, it had been made sure that pedestrians’ behavior histories might affect their thermal sensation / thermal comfort / thermal preference.
From these results, it is made sure that even if the thermal environment inside the shopping arcade is not comfortable in summer, it is possible to propose the countermeasures for the arcade with little thermal load for pedestrians by arranging roadside trees in adjacent city blocks to block out solar radiation, and place facilities for pedestrians to take rest and stay at the entrance and inside of the arcade within a few-minute walk, for example.
In part1, the long-term field test of thermosyphon solar water heaters (SWHs) was conducted. In the test, S1-system in which solar hot water is sent only to a bathtub and shower, S2-system in which users can select hot water from SWH or an auxiliary gas boiler by switching a valve depending on the solar water temperature, and S3-system in which the auxiliary gas boiler works automatically by the device called connection unit were given as the secondary distribution systems. Due to the various test conditions, however, straightforward comparisons of each SWH and distribution systems were impossible. Therefore, in this paper, we aimed to analyze the annual performance by computer simulations in an objective manner.
In the first half, two SWHs used in the field test were modeled by Type45 in TRNSYS ver. 18. The collector efficiency parameters were estimated theoretically from the sectional diagrams contributed by the manufacturer. The insulation performance parameters of tank were given from design information with fine-adjustment. In order to confirm the validity of calculation method, each system was simulated with the solar radiation, the ambient temperature, the main water temperature and the flow rate from the field test data. Over 50days results were compared to the field test performance to show an uncertainty of 5% for S1 and S3 systems and 10% for S2-system.
In the second half, annual simulations were executed with data of 1st Apr., 2017 to 31st Mar., 2018. There were three cases of hot water demand pattern corresponding to Japanese family of four, three, and two. S3-system showed the largest solar contribution in all three distribution systems and SCOP in the case of family of four was 1.26-1.34 and the primary energy reduction rate was 28.1-32.1%. S2-system consistently showed the poorer performance than the others because the solar water temperature lower than 40oC was not available. SCOP in the case of family of four was 1.10-1.17 and the primary energy reduction rate was 17.7-22.4%. Though S1-system has smaller hot water demand, its energy performance was close to that in S3 system because of little primary energy consumption derived from electricity. Its SCOP in the case of family of four was 1.23-1.25 and the primary energy reduction rate was 26.0-27.2%. From a viewpoint of conversion efficiency of solar radiation, selection of relatively small sized SWH is suitable. Solar efficiency of S3-system was 30.5-34.2% in the case of family of four and 24.9-27.4% in the case of family of two.
Risk assessments of chemical substances are essential and, in particular, risk estimation is of paramount importance to ensure the health of workers. However, measurement of the concentrations of chemical substances in the working environment, which are generally based on field/personal exposure measurements, are not always feasible. To precisely predict the transient concentration distribution of chemical substances, we developed a numerical model for the emission of gas-phase chemical pollutants from mixed solutions in case of a liquid chemical leakage accident. In this study, we conducted computer fluid dynamics (CFD) analysis incorporating the proposed model and using experimental results for the time-dependent concentration of the emissions at various ambient temperatures.
As first step of numerical modeling development, we focused on ammonia as chemical substances and conducted fundamental experiments in a small chamber to identify the transient gas-phase emission characteristics from binary mixture solution.
The experimental value showed that higher ambient temperatures led to higher initial ammonia concentration. However, after 40 minutes, the temperature dependence was minimal, and at higher temperatures, the exhaust concentration approached zero sooner.
In this study, the saturated gas-phase concentration of ammonia estimated from the Henry model was incorporated into the CFD as the wall surface boundary condition. The experimental test chamber geometry was precisely reproduced for the numerical analysis. Here, the flow field in the test chamber was assumed to be in the steady state. Based on the steady air flow profile, non-steady state analyses of the emission and diffusion of ammonia in the chamber were analyzed. The numerical analysis results showed the same tendency, and nearly reproduced the experimental values.
This study proposed an unsteady non-uniform concentration distribution analysis method based on CFD to predict the amount of a toxic gas-phase chemical compound generated from a liquid solution in consideration of temperature effect.
This paper describes development of district co-generation (DCG) including heat source equipment and heat spply pump, and the effect analysis by the diffusion of district co-generation system in Japanese business area. Developed model in this paper calculated DCG operation at 5-minute interval. And the effect analysis used three energy index. The estimating of district co-generation system spread effect confirmed the energy saving effect by district co-generation in Japanese business area.
1st chapter describes a background of this paper. The city in Japan needs to construct distributed energy supply systems. And DCG is considered to be one of effective distributed energy systems, but the details of its spread effect has yet to be clarified. Therefore, we developed a DCG operation model in urban scale to the effect analysis by the diffusion of DCG system in Japanese business area.
2nd chapter indicates the development of DCG model. We made a DCG model based on past programs. This model include Heat source equipment such as air heat pump, turbo refrigerator. And the model calculated CGS operation in 5-minute interval. Furthermore, it also considered heat supply piping length, transport power, piping heat loss in DCG calculation.
3rd chapter is the making of three energy indexes. In order to assess energy saving effect of DCG system, This paper made the index about esannual primary energy consumption, annual life cycle CO2 emissions, and annual standard deviation of power supply and demand.
4th chapter describes case studies. We analyzed four areas with different characteristics of located buildings. Prestage of the analysis estimated the 5-minute power demand and each heat demand for cooling and heating of each non-residential building in these target areas. Moreover, we analyzed thousands of calculation results of each area in a case study and confirmed the energy saving effect, CO2 saving effect, and power system operation stability improvement effect by DCG system in Japanese business area.
5th chapter is conclusion. It summarizes the main points so far and shows future issues.
In recent years, high dense cities such as Tokyo and Hong Kong are facing serious problems regarding thermal comfort and air quality of outdoor space caused by the poor ventilation in cities. Urban ventilation has been regarded as an effective countermeasure against such problems in many studies. The majority of previous attempts for improving urban ventilation have focused on the methods to lead the horizontal wind inside the urban area by reducing building coverage ratio, that is, to secure “horizontal ventilation paths”. However, it is almost impossible to considerably reduce building coverage ratio in already developed high dense urban districts in cities such as Tokyo and Hong Kong. In the urban districts along the coastal areas, it is more realistic to allow sea breeze above the urban canopy layer to blow down to the ground level, that is, to secure “vertical ventilation paths”. In recent years, the non-uniformity of building height has been attracting attention because of its effect to create “vertical ventilation paths”. Thus, the non-uniformity of building height has the effect of improving the quality of outdoor environment by increasing the wind velocity at the pedestrian level within a focused urban district. However, the urban district with non-uniform building height causes more momentum loss of streamwise wind than an urban district with uniform height. Consequently, this leads to decreased wind velocity in leeward areas of the focused urban district. In this study, Large-eddy Simulations were applied to flowfields in two urban district models consisting of rectangular buildings with uniform and non-uniform heights.
The result of the case with uniform building heights (Fig. 6(1)) showed that the incoming airflow was moving along the top of the buildings and only little airflow was going downward to the area near the ground. On the other hand, the result of the case with non-uniform building heights (Fig. 6(2)) indicated that circulating flow regions were formed above the low-rise and mid-rise buildings, and the airflow moved down to the area near the ground in front of the high-rise buildings along the circulating flows. In section 3.3, the total drag force of buildings of two cases was evaluated as a summation of form drag caused by the pressure difference between windward and leeward sides of the buildings (Eq.(7)) and friction caused by the shear stress on the building and ground surfaces (Eq.(9)). It was confirmed that the total drag force of urban district was drastically increased by the effect of the non-uniformity of building height. This was mainly caused by the increase of the form drag on upper parts of high-rise buildings. In section 3.4, the streamwise momentum balance equation was derived to evaluate the streamwise momentum transport and the contribution of each term of momentum transport equation to the total streamwise momentum transport. From these results, the influence of non-uniformity of building height on the streamwise momentum transport was quantitatively evaluated. As shown in Fig. 15, streamwise momentum transport decreased by the effect of drag force of buildings, and the decrease of streamwise momentum transport in the case with non-uniform building height was about 3.75 times of that in the case with uniform building height, in this study.
In the architectural field, making a consensus is indispensable to stakeholders. Remote meetings are useful with consensus buildings because they don't require travel costs, unlike face-to-face meetings by gathering from a distance. However, conventional remote meetings like video conferences using displays lack a sense of presence. Moreover, it is difficult to intuitively share three-dimensional (3D) information such as the spatial position and shape of design objects required in the architectural field.
For sharing 3D information, 3D physical building models or 3D virtual models are created. In remote meetings, users can see 3D virtual models made by 3D modeling software such as 3D computer-aided design (CAD) or Building Information Modeling (BIM) in stereoscopic images. However, their 3D virtual models have to be made in advance, this is why they cannot represent shapes changing in real-time like 3D physical objects.
Point clouds are clusters of points that generally have their position as an XYZ coordinate with RGB values. They can represent 3D surfaces in the real world. By using an RGB-D camera that can capture RGB images and depth data and capture point cloud data in real-time, the 3D virtual model based on the surface of the 3D physical object can be made without needing to create a 3D model in advance.
Interactivity enables users to provide understandings of the targeted 3D object characteristics. High-speed point cloud segmentation is necessary to classify unordered point cloud data captured by an RGB-D camera in real-time.
In this research, we use the Euclidean Cluster Extraction method for interactive remote sharing of 3D physical objects and provide users with the ability to manipulate 3D point cloud objects with Mixed Reality (MR). We constructed a prototype system using an RGB-D camera to capture point cloud data and MR-Head Mounted Display (HMD). By using the Euclidean Cluster Extraction method with Random sample consensus (RANSAC), point cloud data is classified into individual clusters and then it enables an MR-HMD user in a remote area to see and manipulate 3D point cloud objects manipulating them by a hand gesture, called the “pinch gesture”.
Through experiments, we evaluated the accuracy of the high-speed segmentation results and the user’s operability for point cloud objects including visibility. When two objects are on the desk, the relation between the two objects and the RGB-D camera including its angle is tracked. Also, the number of point clouds transferred into the MR-HMD can affect the user’s operability.
In future works, the proposed system should be modified using a higher accuracy segmentation method which doesn’t depend on the distance, for capturing point cloud data using multiple RGB-D cameras and align them to make the wider surface of point cloud objects, and for use on Wide Area Network (WAN) as well as the internet environment.
Presently, social trends are indicating that single elderly households are increasing while lifestyles are diversifying. This paper proposes the Biofied building concept. In Biofied buildings, home robots provide a safe, secure, and comfortable space for residents. The objective of introducing robots is to sense a resident’s position and movement in real-time. However, with the existing system, it is difficult to prevent unexpected accidents and control robots without disturbing the residents. The objective of this study was to incorporate the motion prediction phase into the system and realize more natural spatial control using robots.
Although a simple motion prediction method based on dynamics using system identification has been proposed by a previous study, this cannot be applied to non-steady motion. Hence, it is necessary to extend the system such that it can be applied to various behaviors observed on a daily basis because the nonlinear behavior is not versatile. Particularly, with regard to walking motion, it has been reported that more than 40% of walking motions in daily life are non-steady, and the 90-degree turn accounts for approximately 20% of non-steady motions. Thus, the 90-degree turn was selected as the prediction target, because it is a basic non-steady walking motion and the most essential motion in daily life.
This study investigated the effectiveness of IMU sensors in measuring movements with complicated posture control. Notably, these sensors are inexpensive and not restricted by the measurement environment; therefore, the proposed method was developed based on data obtained using IMU sensors.
The kinematic parameters extracted in the preliminary experiment are useful for predicting the 90-degree turn by comparing steady walking to the 90-degree turn. Through comprehensive observations, the yaw and roll of the head and upper trunk, and the acceleration of shoulders and shanks, were extracted as the prediction parameters.
The 90-degree turn, which was performed at the subject’s own time and according to their free will, was measured to validate the prediction of parameters under the condition wherein the environmental and mental effects are eliminated. The prediction method was developed using the threshold defined by the amplitude during steady walking. The proposed method was evaluated by considering the prediction accuracy and prediction time. The fastest prediction time of 0.85 seconds was that of the yaw angular velocity at the head, and it was possible to predict it at least one step earlier.
Finally, the dependence of parameters on environmental factors was verified by conducting the same experiment at a corner. Compared with the previous experiment, only the response of the yaw angular velocity at the head was significantly faster, which suggests that this parameter depends on environmental factors. The yaw angular velocity at the head was the best predicted parameter with 100% success in each case. Hence, the motion is more likely to be predicted when the prediction time is longer, because the 90-degree turn is often performed at corners.