Small Space Research Articles

The Algorithm and the Org Chart: How Algorithms Can Conflict with Organizational Structures

Algorithms are introducing changes to individuals? jobs, but do algorithms also lead to changes in the structures of organizations themselves? Organizational structures, as often formalized into organization (org) charts, are meant to facilitate coordinated decision-making. Yet our 10-month ethnographic study of a large online retail company reveals why the organizational structures that facilitate effective decision-making by humans may be in tension with the organizational structures that facilitate effective decision-making using algorithms. Our findings show that the human decision-makers needed small, divided-up sets of decisions, and they had previously accomplished this through how they structured individuals' roles and teams in the org chart. In contrast, when data scientists developed a new algorithm and first deployed it within organizational structures meant to support human decision-making, they realized that these small divided-up decision spaces were arbitrarily constraining the algorithm's search space. When not constrained in this manner, the algorithm could identify and recommend better solutions, but those optimal solutions did not always align with the structure of roles and teams in the org chart. This study suggests that as algorithms are integrated into the workplace, organization designs may begin to more explicitly reflect the contours of those algorithms' behaviors.

Analysis of the traction forces of two adjacent linear induction motors

Linear induction motors (LIMs) are positioned head-to-tail in medium and low-speed maglev (MLSM) trains, and the interaction due to small spacing between two LIMs is not yet clear. In this work, based on the 2D electromagnetic field theory, the vector magnetic potential (VMP) of each region was solved, and the traction forces of two adjacent LIMs were derived. Subsequently, the correctness of the theoretical model was verified by simulation. Finally, the effects of the spacing, wiring type, pole pitch, speed, etc., on the traction forces of two adjacent LIMs were analyzed. The results show that the traction force of LIM1 (arranged in front) is almost unaffected by LIM2 (arranged behind LIM1), while that of LIM2 fluctuates periodically with the spacing, and the smaller the spacing, the greater the fluctuation amplitude. Meanwhile, the larger the pole pitch, the more the pole number, the greater the slip frequency, and the lower the speed, the smaller the effect of LIM1 on LIM2. When the spacing takes 1.1 to 1.6 times the pole pitch, the traction force of LIM2 is larger than that of LIM1. The achievements can provide technical support for enhancing the traction performance of the LIMs in the MLSM trains.

Microvenular hemangioma located in the breast: a case report

Abstract Microvenular hemangioma (MVH) is a rare, benign type of hemangioma that typically presents as a solitary, slow-growing, red-to-violaceous asymptomatic papule, plaque, or nodule. It most commonly locations of the lesions on the limbs and trunk, with no prior reports of MVH confined to the breast. We present the first reported case of multiple MVH confined to the breast in a 17-year-old female patient. The case is notable for its unique and atypical clinical features. Diagnosing MVH is challenging and requires routine pathological and immunohistochemical staining. Histological testing revealed typical features of MVH, irregularly branched small or medium vascular interstitial spaces lined with benign endothelial cells and positivity for CD34 and CD31. This case emphasizes the need to consider MVH in the differential diagnosis of breast vascular lesions, particularly in young patients. It also underscores the importance of histological and immunohistochemical analyses for an accurate diagnosis.

A novel global multi-level terrain data tile production method

Abstract. Terrain services have increasingly wide applications in urban planning, 3D gaming animation, and other fields. Map websites typically provide terrain services to users in the form of terrain shaded relief tiles. Map tile technology offers a new solution for large-scale concurrent user access. Although terrain shaded relief tiles can effectively represent changes in terrain relief, users cannot adjust the visualized raster images for visualization schemes, making data analysis and applications more challenging. The emergence of Terrain-RGB technology has effectively addressed this limitation. However, currently, internet maps mostly provide multi-level map services to users in the form of web map tile service (WMTS). Terrain-RGB images produced by simple encoding tools may exhibit grid lines when rendered on tiles with a small grid spacing, affecting the usability of Terrain-RGB products. Therefore, this paper proposes a technical approach for producing global multi-level Terrain-RGB products using digital elevation model (DEM), focusing on addressing the issues of gridlines and splicing traces from different scenes DEM data, offering a new solution for map websites to release analyzable terrain services.

Multi-class Object Detection in Urban Scenes Based on Deep Learning

Abstract. The rapid development of urbanization presents challenges and requirements for multi-class object detection in urban scenes. Accurately identifying buildings, vehicles, and trees in urban scenes can optimize urban planning, traffic management, monitoring environmental conditions, and promote the development of smart cities. Traditional target detection methods perform poorly in complex urban environments, while deep learning technology achieves accurate target recognition and positioning by automatically extracting high-level semantic features. In this study, we chose to use the YOLOv5s algorithm for multi-class target detection in urban scenes. YOLOv5s is a lightweight deep learning model with small storage space and efficient detection speed. In this paper, the Potsdam area data published by ISPRS is used to make the label data of buildings, vehicles and trees. The YOLOv5s algorithm is used to iteratively train the model. The results show that the mAP value detected by the YOLOv5s model can reach 82.83%. The experimental results show that the algorithm shows higher accuracy than SSD and Faster R-CNN in tree detection. Although it has a slight decline in building and vehicle detection, considering the factors such as detection accuracy, speed, and model size, the YOLOv5s algorithm has a better recognition and detection effect for the detection of multi-class targets in urban scenes.

Pore-scale study of droplet settling on a heterogenous surface structure

Equilibrium contact angle of a droplet is influenced by surface characteristics and fluid properties. In addition to increasing the solid–liquid contact line, surface roughness also alters the surface free energy, which has a significant influence on contact angle values. Droplets are more likely to impinge on vertices as surface roughness increases. Anisotropic wetting of chemically heterogeneous surfaces further controls the total surface free energy. The free energy Lattice Boltzmann method is utilized to study the effects of wettability heterogeneity and roughened surfaces. Initial model comparisons with experiments showed excellent agreement. The rough surface is modeled with different pillar shapes on a smooth wall, with surface wettability ranging from hydrophilic to neutral conditions. The length scale of surface patterns matches the droplet size, making the Cassie–Baxter and Wenzel equations inapplicable. Results indicate that droplets pin on the vertices of rectangular pillars, while frustum shapes facilitate movement. Studies cover nearly neutral wet, moderately wet, and strongly wet conditions. The effects of relative surface roughness, roughness distribution, mixed wetting surfaces, and body force on equilibrium contact angle are examined. Additionally, the interaction between fluid flow and surface roughness elements shows that smaller spacing and greater height of roughness elements enhance thermal performance, with Nusselt numbers fluctuating significantly. Findings suggest that the ratio of droplet size to pillar surface area is crucial for minimizing surface free energy. On superhydrophilic surfaces, droplet pinning at pillar edges causes the surface to behave hydrophobically. In mixed-wet rough surfaces, pillar wettability significantly influences the equilibrium contact angle.

Does every public open space (POS) contribute to sustainable city development? An assessment of inefficient POS in Beijing

Public open space (POS) plays a crucial role in influencing the urban environment, ecology, public health, and economic vitality. However, not every POS is being efficiently utilized, while the inefficient POSs occupy large areas and can negatively affect socio-economic development, thus posing a threat to sustainable city development. Existing studies evaluate POSs solely based on benefit outcomes, but ignore POS functional types and contextual environments. To address this issue, a categorized, integrated, and relative evaluation method, i.e., utilization efficiency (UE), is proposed to identify inefficient POSs, where essentially measures the ratio from benefit outcome to resource occupation of each POS. We firstly classify POSs into five types by considering their core functions, then measure their UEs to extract efficient and inefficient POS, and finally visualize key causes of different types of POS. Our results reveal 3,138 inefficient out of 10,943 POSs in Beijing, and show the inefficient POSs that are concentrated in the southern Beijing and northern regions between the 5th and 6th ring roads, mainly affected by local population density and environmental resource. Drawing on the features of inefficient POSs, it is suggested to increase small green spaces and sky gardens in the downtown areas, improve service facilities and basic tourism infrastructure in the suburbs. Accordingly, this study firstly incorporates POS functional types and resource occupation into the utilization efficiency evaluation, providing spatial optimization recommendations of POSs to facilitate sustainable city development.

Droplet trampoline surface for regulating contact time of a bouncing droplet across a wide spectrum of Weber numbers verified by in-situ observation

The dynamic superhydrophobicity of metallic surfaces is crucial for anti-icing and anti-adhesion in the fields of aerospace and transportation. Generally, fabricating micro/nanostructures on metallic surfaces is an effective method for facilitating rapid detachment of droplets, and the micro/nanoscale composite structure can significantly reduce the solid–liquid contact area. Meanwhile, the exploration of the correlation between solid–liquid contact time and the spacing of microstructures across a wide range of Weber numbers is of great significance. In this study, it is observed that the contact time of a bouncing droplet on microstructures with small spacing exhibits a notable correlation with the Weber number. This observation challenges the prevailing understanding that the contact time of a bouncing droplet is commonly perceived as independent of the Weber number, equated to the impact velocity. Increasing the structure spacing appropriately proves advantageous in preventing pinning effect, consequently reducing the duration of solid–liquid contact. Subsequently, a regulatory diagram is generated to demonstrate the correlation between contact time and the dual dimensions of the structure spacing and Weber number. Specifically, a novel theory for predicting the contact time based on the Weber number has been established, which reveals the unconventional correlation and enriches the knowledge of droplet dynamics.

Experimental study on stable combustion of pulverized coal stream in a confined small space with air jet

Experimental study on stable combustion of pulverized coal stream in a confined small space with air jet

Real and Virtual Lecture Rooms: Validation of a Virtual Reality System for the Perceptual Assessment of Room Acoustical Quality

Enhancing the acoustical quality in learning environments is necessary, especially for hearing aid (HA) users. When in-field evaluations cannot be performed, virtual reality (VR) can be adopted for acoustical quality assessments of existing and new buildings, contributing to the acquisition of subjective impressions in lab settings. To ensure an accurate spatial reproduction of the sound field in VR for HA users, multi-speaker-based systems can be employed to auralize a given environment. However, most systems require a lot of effort due to cost, size, and construction. This work deals with the validation of a VR-system based on a 16-speaker-array synced with a VR headset, arranged to be easily replicated in small non-anechoic spaces and suitable for HA users. Both objective and subjective validations are performed against a real university lecture room of 800 m3 and with 2.3 s of reverberation time at mid-frequencies. Comparisons of binaural and monoaural room acoustic parameters are performed between measurements in the real lecture room and its lab reproduction. To validate the audiovisual experience, 32 normal-hearing subjects were administered the Igroup Presence Questionnaire (IPQ) on the overall sense of perceived presence. The outcomes confirm that the system is a promising and feasible tool to predict the perceived acoustical quality of a room.

Group interaction effect on breaking wave forces on a vertical pile: Experimental tests and predictive models

Pile groups are extensively utilized as supports for many coastal structures, such as bridges, jetties, and oil production platforms. The problem of understanding the interaction effects within pile groups and predicting the breaking wave forces on them is considered in this paper, using experimental tests and machine learning-based predictive modeling. The restriction of previous studies on this important engineering problem is that the pile group arrangements considered are limited. Prediction methods are therefore developed only for specific pile group arrangements and do not incorporate the effect of the incident wave direction. In this study, to partially overcome this limitation, an extensive experimental investigation is conducted on 70 different pile group arrangements under six breaking wave conditions. Three pile group coefficients, characterized by the total, quasi-static, and dynamic forces, are introduced for a thorough assessment of the interaction effects within the pile group. First, the pile group coefficients for three basic arrangements (tandem, side-by-side, and staggered) are evaluated. The results reveal a sheltering effect in the tandem arrangement and an amplification effect in the side-by-side arrangement. However, the forces on the measured pile in the staggered arrangement resemble those on the isolated pile, with neither significant sheltering nor amplification effects observed. Then, the results for all arrangements highlight the significant effect of wave direction on the pile group coefficients for small inter-pile spacing. Finally, different machine learning algorithms are adopted to develop predictive models for the group coefficients. The XGBoost model demonstrates superior accuracy for predicting the total and quasi-static force coefficients, while the dynamic force coefficient remains challenging to predict accurately due to its stochastic nature.

Large-scale simulations of vortex Majorana zero modes in topological crystalline insulators

Topological crystalline insulators are known to support multiple Majorana zero modes (MZMs) at a single vortex, their hybridization is forbidden by a magnetic mirror symmetry MT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$M_{T}$\\end{document}. Due to the limited energy resolution of scanning tunneling microscopes and the very small energy spacing of trivial bound states, it remains challenging to directly probe and demonstrate the existence of multiple MZMs. In this work, we propose to demonstrate the existence of MZMs by studying the hybridization of multiple MZMs in a symmetry breaking field. The different responses of trivial bound states and MZMs can be inferred from their spatial distribution in a vortex. However, the theoretical simulations are very demanding since it requires an extremely large system in real space. By utilizing the kernel polynomial method, we can efficiently simulate large lattices with over 108 orbitals to compute the local density of states which bridges the gap between theoretical studies based on minimal models and experimental measurements. We show that the spatial distribution of MZMs and trivial vortex bound states differs drastically in tilted magnetic fields. The zero-bias peak elongates when the magnetic field preserves MT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$M_{T}$\\end{document}, while it splits when MT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$M_{T}$\\end{document} is broken, giving rise to an anisotropic magnetic response. Since the bulk of SnTe are metallic, we also study the robustness of MZMs against the bulk states, and clarify when can the MZMs produce a pronounced anisotropic magnetic response.

Integrating Virtual Reality and Colour Psychology in the Design of Small Liveable Spaces

Virtual reality (VR) technology has quickly advanced, providing new ways for immersive and interactive experiences. This research aims to integrate colour theories into the practical application of Vanspace 3D software. The study investigates the perceptual dimensions of colour schemes, lighting, and their collective impact on spatial perception within confined living spaces. Through a step-by-step equipping and furnishing process, the software's versatility is demonstrated, accommodating various design elements, from solar panels to custom furniture. Monochromatic and analogous schemes align with nature-inspired living, while triadic schemes emphasise balance. Complementary and tetradic schemes showcase harmonious and rich designs, and warm and cold colour schemes present contrasting atmospheres, highlighting design adaptability. Exploration of contrast, saturation, and lighting underscores their influence on aesthetics and functionality. Findings suggest that colour choices significantly impact perceived size and ambience, offering recommendations for creating spacious illusions in confined spaces.

Comparison of surgical performance using articulated (ArtiSential®) and conventional instruments for colorectal laparoscopic surgery: A single-centre, open, before-and-after, prospective study.

Rigid surgical instruments limit movement whereas articulated instruments offer better control in small spaces and allow for intuitive and ergonomic movements. However, the effectiveness of the use of articulated instruments in improving colorectal laparoscopic outcomes remains unclear. The aim of this work was to determine whether colorectal laparoscopic surgical proficiency improved when multijoint instruments were used instead of conventional ones. We enrolled 70 consecutive patients (n = 20 for conventional instruments) aged 19-80 years who underwent elective laparoscopic surgery for colorectal diseases. Unedited surgery videos were validated using the modified Global Operative Assessment of Laparoscopic Skills (mGOALS) scale. Learning curves were analysed using a cumulative sum control chart for mGOALS grades. The surgery type, length of hospital stay and 30-day postoperative complication rates were comparable between the groups, and the surgeon's mGOALS grades were similar (p = 0.190). However, in the articulated group, the scores were significantly higher for depth perception (p = 0.012) and tissue-handling domains (p = 0.046), while surgical duration was significantly shorter and intraoperative blood loss was significantly lower (p = 0.022), compared with those in the conventional (p = 0.002) group. Learning curve findings indicated that the first 10 and subsequent 40 surgeries in the articulated group were within the inexperienced and experienced phases, respectively. The mGOALS score in the experienced phase improved in the articulated group compared with that in the conventional group (p = 0.036). The use of articulated instruments in laparoscopic colorectal surgery showed potential benefits. Further studies are needed to confirm these findings.

Numerical simulation on multi-well fracturing considering multiple thin layers in vertical direction

Multiwell fracturing is a key technology for developing shale gas and shale oil reservoirs. In this study, a multiple planar 3D (PL3D) fracture simulator that can capture multiple thin layers was developed to examine the propagation of multiple fractures during multicluster fracturing in multiple horizontal wells. The simulator considers multiple thin layers in the vertical direction. The results of the model are validated against the analytical solution of a single radial fracture and the implicit level set algorithm (ILSA). Using the simulator, a series of numerical simulations based on the field case are performed to investigate the fracture propagation mechanism of multiwell fracturing. The completion sequence, well placement pattern, well spacing, and cluster spacing are investigated to optimize the treatment parameters. The effective fracture area is used to quantitatively describe the stimulation effect. The adaptability of the completion sequence and well placement pattern is also analysed from the perspective of “frac hits”. The results show that the completion sequence has a critical influence on the stimulation effect and fracture geometry. From the perspective of avoiding “frac-hit” fractures, fracturing the low-stress layer can form an “artificial stress barrier”, which slightly protects the well from interference from other fractures. The staggered well pattern is better than the stacked well pattern. Compared with the stacked pattern, the staggered pattern can reduce the overlap area of fractures by 80 %, which greatly reduces the probability of “frac-hits”. With increasing well spacing from 200 m to 500 m, the fracture area increases by 25 %, and the degree of uneven stimulation between the two pay zones also increases by 6 %. Considering that a small well spacing is prone to “frac hits”, a large well spacing leads to an unstimulated area between two wells, and a 350 m well spacing is optimal. The effective fracture area decreases slightly with increasing perforation cluster spacing, but the fracture geometry becomes much more regular. The results can be helpful for the field design of multiwell fracturing.

Performance of newly developed add-on devices on aerosol delivery in noninvasive ventilated subjects

Background: Several techniques had been developed to generate aerosolized medications during noninvasive ventilation (NIV) using variable inhalation methods. This study hypothesized that large spacers were more efficient significantly than small spacers and adapters during NIV. Objective: The main objective of this study was to compare the performance of newly developed spacers with standard T-piece in NIV chronic obstructive pulmonary disease (COPD) subjects. Methods: Sixty COPD subjects requiring NIV were included in this study. A dual-limb circuit was used, and the mode of ventilator was set in spontaneous volume-controlled mode. Dual-limb ventilation circuit, consists of inspiratory-limb and expiratory-limb, is pressure and volume controlled in response to subject expiration providing relatively high resistance to expiratory flow. Two experimental sets were evaluated: the first was introducing two preliminary pressurized metered-dose inhalers (pMDI) puffs before the nebulization of 1 ml of a respirable solution of salbutamol by vibrating mesh nebulizer (VMN) using Minimhal and Combihaler. The second was to only nebulize 1 ml of salbutamol respirable solution by VMN using Combihaler, Minimhal, and standard T-piece. Two urine samples were collected after aerosol delivery: urine sample after 30 min. (USAL0.5) as an indicator of lung deposition and all urine pooled 24 h (USAL24) post-inhalation as an indicator of systemic absorption. The amount of salbutamol extracted from urine samples was assayed by high-performance liquid chromatography. Results: Minimhal + pMDI + VMN delivered a higher percentage of salbutamol 30 min post-inhalation than Minimhal + VMN (p < 0.001). Also, Combihaler + pMDI + VMN delivered a higher percentage of salbutamol 30 min post-inhalation than Combihaler + VMN (p < 0.001). Combihaler + VMN delivered a higher percentage of salbutamol 30 min and 24 h post-inhalation than both Minimhal + VMN and T-piece + VMN (p < 0.001). Standard T-piece delivered the lowest aerosol amount delivered to the lung compared to both spacers (p < 0.05). Conclusions: Introducing two pMDI puffs significantly improved aerosol delivery by both spacers. Combihaler significantly improves aerosol delivery more than Minimhal.

An image encryption algorithm for colour images based on a cellular neural network and the Chua's chaotic system

In the internet era, image encryption technology plays a crucial role in ensuring the security of image information. Aiming at the problem that low-dimensional chaotic encryption has a relatively small key space and is vulnerable to chosen-plain attacks, this paper proposed a novel colour image block encryption algorithm based on the cellular neural network and the Chua's chaotic system. Firstly, the plain is separated into three primary colours. And Fourier transform is applied to achieve optical transformation, generating six chaotic sequences iteratively. Secondly, the chaotic sequences were combined in pairs. And then combined with the plain to form three sequences, which were used in the diffusion process. Finally, the improved Chua's chaotic system is used to scramble the image. Both diffusion and scrambling are performed synchronously during encryption. Through the above operation, we get the final colour encrypted picture. The experimental results show that the algorithm has excellent encryption effect and can resist common attacks.

Simulation and experimental study on surface modification of 6061‐T651 aluminum alloy by machine hammer peening

AbstractMachine hammer peening is a surface treatment technique employed to enhance the surface properties of the treated samples. In this present work, the theoretical analysis, finite element simulation and experiment of single peening are carried out to investigate the relationship between the machine hammer peening force and geometric dimensions of the single peening indentation deformation, including diameter and depth. The single peening experimental results are in accordance with theoretical and simulation analysis. The machine hammer peening experiment with grate tool path are done and the results including surface topography, surface roughness, surface hardness, x‐ray diffraction analysis and wear resistance are discussed. This work seeks to explore the effects of process parameters like machine hammer peening force, indentation and pitch spacing on surface roughness and hardness. The results reveal that the surface hardness and roughness are positively associated with machine hammer peening force and small indentation and pitch spacing lead to high hardness. The x‐ray diffraction analysis validate machine hammer peening is a mechanical treatment without new compound generated. The friction test results in an enhancement in wear resistance of treated samples.

Heat Transfer in Double Pipe Heat Exchangers with Small Tube Spacing

Abstract In this current work, the heat transfer in double pipe heat exchangers with small tube spacing is analysed. This type of heat transfer is generally described in many literary sources, however, in laminar flow, the resulting values of the theoretical equations differ. Moreover, the small spacing of the pipes can affect the fluid flow and subsequent heat transfer. The suitability of using available theoretical methods for the design of double pipe heat exchangers (the Stephan, VDI and Baehr methods) was evaluated. A series of experiments was carried out on a double pipe heat exchanger with a tube spacing of 1.4 mm. The experimentally determined value of the heat transfer coefficient was up to two times higher in comparison with the values calculated according to theoretical methods. The relative increase was more significant for the lower Reynolds number values. At the same time, the difference of the wall temperature along the circumference of the outer tube was detected. This phenomenon was theoretically analysed and can be explained by tube misalignment in the small tube spacing. The procedure of quantification of this effect was proposed. This effect may cause an inhomogeneity of the media flow and temperature distribution and, as a result, increase the performance of the heat exchanger by tens of percent.

Vertical Plant Configuration: Its Impact on Microclimate and Thermal Comfort in Urban Small Green Spaces

The presence of small green spaces throughout high-density urban areas is essential for enhancing thermal comfort and combating the urban heat island effect. Extensive research has been conducted on plants, which play a key role in cooling green spaces. However, the majority of research focuses on trees, overlooking the efficiency of vertical plant configurations, especially shrubs. Hence, this paper selected a typical small green space in Tokyo’s high-density urban area and employed scenario simulation to examine how various vertical plant configurations impact the microclimate and thermal comfort of small green spaces, with a particular emphasis on quantifying the efficiency of shrubs. The research primarily discovered four findings. First, trees significantly outperform shrubs in improving thermal comfort, especially during periods of strong sunlight during the day, leading to a direct modification of the thermal comfort levels. Second, while shrubs (height &lt; 2 m) usually do not make a substantial difference in the overall thermal comfort levels of small green spaces, they are effective in reducing areas classified as “hot” and “very hot” during the day, with their cooling effect becoming more pronounced in the late afternoon. Third, when small green spaces combine trees and shrubs in their plant configuration, taller shrubs (within 0–2 m) exhibit a more pronounced cooling effect and improvement in thermal comfort. The conclusions of this study could offer guidance for the planning, design, and renovation of small green spaces in high-density urban areas.