Vacant Space Research Articles

Achieving an Ultralow-κ yet Strong and Transparent Film by Antisolvent-Confined Nanowelding of Electrospun Polyimide Nanofibers.

Developing ultralow-κ (dielectric constant) polyimides (PIs) that are mechanically robust while also being optically transparent is challenging. For the first time, we report a nanoporous PI film with an ultralow κ of 1.8 in combination with a tensile strength of up to 180 MPa, a Young's modulus of up to 6 GPa, and a transmittance of ∼88%. This is achieved by direct nanowelding of a porous electrospun PI nanofiber membrane using a simple mixture of ethanol-dominating DMAc. Benefiting from the effective evaporation of the antisolvent ethanol upon heating, the proposed nanowelding approach allows for the localized surface dissolution of the PI nanofibers, which enables the dissolved PI to "glue" the nanofibers and occupy vacant space in the membrane, resulting in the formation of a dense but nanoporous self-reinforced nanocomposite film. Our findings provide a renewed understanding of the potential of electrospun nanofibrous materials, and the underlying principle can hopefully be applied to other commodity polymers.

Size-Dependent Isovalent Impurity Doping for Ambipolar Control in Cu3N.

Substitutional doping, involving the replacement of a host with an aliovalent impurity ion, is widely used to attain ambipolar controllability in semiconductors, which is crucial for device application. However, its effectiveness for p-type doping is limited in monovalent cation compounds due to the lack of suitable aliovalent (i.e., zerovalent) impurities. We propose an alternative approach for p- and n-type doping, mediated by the sizes of isovalent alkali metal impurities in Cu(I)-based semiconductors, such as copper nitride with an electron concentration of ∼1015 cm-3. Doping of isovalent Li with a smaller size to interstitial positions improves n-type conductivity, and electron concentration is controllable in the range of 1015 to 1018 cm-3. In contrast, larger isovalent Cs and Rb impurities facilitate p-type conversion, resulting in a hole concentration controllability of 1014 to 1017 cm-3. First-principles calculations indicate that Li is placed as an interstitial impurity acting as a shallow donor in conjunction with the formation of a neutral impurity on Cu defects. As the impurity size increases beyond the capacity of the vacant space, the formation of multiple acceptor-type Cu vacancies is enhanced owing to the repulsion between host Cu+ and Cs+/Rb+ impurities. Consequently, the Cs or Rb impurity is located at the sites of the N accompanied by six neighboring Cu vacancies, forming acceptor defect complexes. This size-dependent isovalent impurity doping scheme opens up an alternative avenue for advancement in optoelectronic devices using monovalent cation-based semiconductors.

Piezoelectricity in chalcogenide perovskites

Piezoelectric materials show potential to harvest the ubiquitous, abundant, and renewable energy associated with mechanical vibrations. However, the best performing piezoelectric materials typically contain lead which is a carcinogen. Such lead-containing materials are hazardous and are being increasingly curtailed by environmental regulations. In this study, we report that the lead-free chalcogenide perovskite family of materials exhibits piezoelectricity. First-principles calculations indicate that even though these materials are centrosymmetric, they are readily polarizable when deformed. The reason for this is shown to be a loosely packed unit cell, containing a significant volume of vacant space. This allows for an extended displacement of the ions, enabling symmetry reduction, and resulting in an enhanced displacement-mediated dipole moment. Piezoresponse force microscopy performed on BaZrS3 confirmed that the material is piezoelectric. Composites of BaZrS3 particles dispersed in polycaprolactone were developed to harvest energy from human body motion for the purposes of powering electrochemical and electronic devices.

Dynamics simulation-based packing of irregular 3D objects

The 3D packing problem has a wide range of applications. However, the complex geometry of irregular objects leads to a sharp increase in the number of placement combinations, making it a challenging problem. In this paper, we propose a packing pipeline based on rigid body dynamics simulation to deal with two types of 3D packing problems. One is the variant bin packing problem, which involves placing more objects into a container of given dimensions to maximize space utilization. The other is the open dimension problem, where the goal is to minimize the container that can accommodate all objects. We first use heuristic placement strategies and a fast collision detection algorithm to efficiently obtain initial packing results. Then, we simulate the shaking of the container according to the dynamic principle. Combined with the vacant space filling operation, shaking the container drives the movement of objects in the container to make the arrangement of objects more compact. For the open dimension packing, the container height is optimized by adjusting the constraints of simulation in the basic pipeline. Experimental results show that our method has advantages over existing methods in both speed and packing density.

Poster 284: The Effect of Pressurized Carbon Dioxide Lavage on Osteochondral Allograft Preparation: A Comparative Study

Objectives: Osteochondral allografts (OCA) transplantation is often utilized for treating osteochondral lesions of the knee due to limited cartilage regenerative capabilities. The use of concentrated bone marrow aspirate (cBMA) has gained traction as a method to enhance OCA incorporation and healing. Pulse lavage and pressurized carbon dioxide lavage are cleaning methods used during OCA preparation to rid native marrow elements and improve graft porosity, but their isolated and combined effects are not fully understood. This study aimed to assess the impact of incorporating pressurized carbon dioxide lavage as an adjunct to pulse lavage during OCA preparation. Our hypothesis was that adding pressurized carbon dioxide lavage would enhance the OCA absorption capacity for liquid-based materials like cBMA. Methods: OCA plugs were harvested from medial hemi-condyles. The plugs were divided into two groups: one group underwent pulse lavage alone, and the other group underwent pulse lavage followed by pressurized carbon dioxide lavage (sequential group). The plugs were weighed before and after each cleaning step and a liquid dye solution with consistency similar to cBMA was added by dripping over the cancellous portion of the graft. Next, the liquid content was determined by centrifugation and spectrophotometry. Results were analyzed statistically. Results: Thirty-four OCA plugs with a 14 to 18 mm diameter were harvested. After the cleaning phase, the sequential group showed a significant weight reduction of 107 ± 21.92% (p < 0.0001) and subsequent weight gain of 96.32 ± 18.99% (p < 0.0001) after the cleaning and dye-dripping procedures. In contrast, the pulse lavage-only group exhibited minimal weight loss and a small weight gain of 10.55 ± 3.86% after the dye-dripping procedure. Conclusions: Adding pressurized carbon dioxide lavage to reduce marrow elements and improve graft porosity significantly improved the OCA cleaning process and created more vacant space enhancing OCA absorption capacity for orthobiologic agents such as cBMA. The study findings highlight the potential of incorporating pressurized carbon dioxide lavage as an adjunct to pulse lavage during OCA preparation. These findings may contribute to the surgical procedure of incorporating cBMA or other orthobiologics to promote the integration and healing of OCA plugs.

Encrypted image processing using compression and reversible data hiding

Reversible data hiding within encrypted images reversible data hiding in encrypted images (RDH-EI) is a highly effective technique for image processing in the field of encryption. This paper, propose a RDH-EI technique, which utilizes bit-plane compression and various image scanning directions to generate vacant space for data embedding, referred to as vacating room. Initially, the prediction error of the pre-processed image is computed. Subsequently, each bit-plane image is converted into a bit-stream by following the pixel scan order employed before compression. The compressed image is then encrypted employing a stream cipher. Through the process of substitution, the secret data and additional information are incorporated into the acquired image without any knowledge of the original content or the encrypted key. Finally, the generated image is transmitted or archived. The experiments provide evidence that the proposed method surpasses the most advanced methods currently available.

Enhanced stretchability of porous PDMS/CIP composites via weak interfacial bonding and their electromagnetic noise suppression properties

The development of wearable devices operated through massive data communication necessitates the use of lightweight, highly efficient stretchable composites to suppress electromagnetic (EM) noise. In this study, highly stretchable porous polydimethylsiloxane (PDMS)/carbonyl iron powder (CIP) composite-based EM noise suppressors were explored. The porous structure reduced the volume fraction of PDMS in the composites, leading to a reduction in the total weight of the composites. The introduction of CIP to porous PDMS initially degraded stretchability owing to stress concentration at the strongly bonded interfaces between the CIP surface and PDMS. However, reducing the interfacial bonding strength by removing the SiO2 layer on the CIP surface significantly enhanced stretchability, causing the resulting composite to display 1.2–1.6 times higher rupture strain values at the same CIP loading contents than those with high interfacial bonding strength. The EM absorption properties of the porous and nonporous PDMS/CIP composites were characterized, and the porous PDMS/CIP composites exhibited ∼1.5 times higher EM noise suppression performance than the nonporous composites. This improvement is attributed to the vacant space within the porous framework filled with air, which enhances impedance matching and extends the transmission route of EM waves.

Youth-driven creative placemaking: Strategies in reshaping urban vacant space

Youth-driven creative placemaking: Strategies in reshaping urban vacant space

A Branch-and-Price Algorithm for an Integrated Online and Offline Retailing Distribution System with Product Return

This study identifies critical inefficiencies within a dual-channel operation model employed by a fast fashion company, particularly the independent operation of three logistics distribution systems. These systems result in high operational costs and low resource utilization, primarily due to redundant vehicle dispatches to meet the distinct demands of retail store replenishment, online customer orders, and customer return demands, as well as random and scattered return requests leading to vehicle underutilization. To address these challenges, we propose a novel integrated logistics distribution system design and management method tailored for dual-channel sales and distribution businesses. The approach consolidates the three distribution systems into one cohesive framework, thus streamlining the delivery process and reducing vehicle trips by combining retail and customer visits. An optimization algorithm is introduced to factor in inventory and distribution distance, aiming to achieve global optimization in pairing retail store inventory with online customer orders and unifying the distribution of replenishment products, online products, and returned products. The paper contributes to the field by introducing a new variation of the Vehicle Routing Problem (VRP) that arises from an integrated distribution system, combining common VRP issues with more complex challenges. A custom Branch-and-Price (B&P) algorithm is developed to efficiently find optimal routes. Furthermore, we demonstrate the benefits of the integrated system over traditional, segregated systems through real-world data analysis and assess various factors including return rates and inventory conditions. The study also enhances the model by allowing inventory transfers between retail stores, improving inventory distribution balance, and offering solutions for scenarios with critically low inventory levels. Our findings highlight a significant reduction in total operating cost savings of up to 49.9% and vehicle usage when using the integrated distribution system compared to independent two-stage and three-stage systems. The integrated approach enables the utilization of vacant vehicle space and the dynamic selection and combination of tasks, preventing unnecessary mileage and space wastage. Notably, the integration of inventory sharing among retail stores has proven to be a key factor in generating feasible solutions under tight inventory conditions and reducing operational costs and vehicle numbers, with the benefits amplified in large-scale problem instances.

Investigating and mitigating blockchain poisoning attacks

With the burgeoning adoption of smart contracts and the intrinsic anonymity that blockchain technology provides, the past few years have witnessed an exponential surge in the deployment of blockchain platforms for managing crypto assets. While Ether stands as a paragon of blockchains equipped with smart contract capabilities, its noteworthy to mention that such blockchains present a blank canvas in the form of a data list, dedicated for unbridled program storage. This vacant space, though pivotal for various operations, can become a potential Achilles heel. Specifically, if this repository gets tainted with malicious data, the repercussions can reverberate across the entire blockchain, disrupting its core functions. The research in focus shines a spotlight on a particularly insidious threat, termed blockchain poisoning attack. Through this stratagem, malevolent actors can, with minimal expense, embed detrimental files within the data space, thereby extensively polluting the blockchain. This isnt just a theoretical hazard; its practical implications are stark and can jeopardize the integrity of countless transactions. In a commendable feat of investigative rigor, the research meticulously decoded the modus operandi behind these blockchain poisoning attacks. By employing a multi-pronged research approach, encompassing in-depth studies and iterative inquiries, it successfully deconstructed the exact techniques that malefactors employ.

Feasibility Study of Implementing Vapor Recovery Unit (VRU) To Control Evaporation in Fuel Storage Tanks

The PT X Fuel Terminal stores, stocks, and distributes fuel before it is delivered to end users. Fuel evaporation happens when Pertamax fuel is stored in storage tanks with vacant space when the liquid level drops. Product shrinkage (losses) from working loss is a frequent issue at the PT X gasoline terminal and is manageable with a vapor recovery unit. The entire working loss was determined to be 0.15% of the Pertamax throughput using information on working loss and investment in Vapor Recovery Unit equipment. With the implementation of the Vapor Recovery Unit, Pertamax losses can be controlled by 95%. The calculation results show that the recovery of Pertamax losses increases from IDR 4,755,933,859 to IDR 12,713,598,714 annually. Furthermore, the annual cost of the Vapor Recovery Unit is IDR 1,348,832,832, with an investment of IDR 6,975,719,896.61. The economic feasibility of its implementation was evaluated through investment profitability, the results showed a positive net present value of IDR 25,255,745,786.25, an IRR of 57%, a PI of 4.62, and a payback period of 2 years, 5 months, and 15 days.

Predicting Vacant Parking Space Availability Zone-Wisely: A Graph Based Spatio-Temporal Prediction Approach

Intelligent parking guidance systems (IPGSs) based on vacant parking space (VPS) availability predictions are highly effective to alleviate the increasingly serious parking difficulties in metropolis. The spatial-temporal correlation analysis of VPS information of multiple parking lots in a region shows that not only the number of VPS in each parking lot has a stable temporal correlation, but also there is obvious spatial correlation among different parking lots. Given this, this paper takes full advantage of the space-time correlation and makes short-term (within 30 min) and long-term (over 30 min) predictions about the number of VPSs in multiple parking lots in an area parallelly. Specifically, this paper develops a deep gated graph recurrent neural network (G <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> RNN) model which has the ability to extract both spatial and temporal correlations concurrently between different parking lots. The advantages of the G <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> RNN model are that, first, spatial and temporal correlations between different parking lots can be accurately obtained simultaneously, and second, there is no need to grid the raw data since it uses graph-structured data. For long-term predictions, two different approaches, namely the single-step and iterative predictions, are investigated. The performance of the G <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> RNN based prediction method is extensively evaluated with practical data collected from eight public parking lots in Santa Monica. The results show that it can achieve considerably high accuracy in both short-term and long-term predictions.

Renewable Energy Sourcing to Enhance Sustainable Manufacturing by Using Madhab’s EEE Impact Analysis Model

The world's increasing energy demand, coupled with the depletion of finite energy resources, necessitates a shift towards sustainable energy solutions. This research explores the multifaceted benefits of substituting conventional fossil fuel-based energy sources with renewable energy in industrial settings, with a focus on sustainable manufacturing. A case study was conducted at a printing and packaging factory in Bhubaneswar, Odisha, to analyze economic, environmental, health, safety, and efficiency factors associated with various energy options based on the Madhab’s EEE (Environmental, Efficiency, Economic) impact analysis method. The study identified solar power generation as the optimal energy source, boasting the lowest EEE impact index of 1.90. Wind energy ranked second, followed by conventional GRID power and DG (Diesel Generator) power sources, which were found to be less favorable due to their higher EEE impact indices. Feasibility assessments revealed that the factory had ample rooftop and vacant land space for solar power plant installation, making it self-sufficient in power generation. The return on investment (ROI) for the solar power project was calculated to be 5.54 years, making it a viable option from a sustainability perspective. Moreover, the solar system could be integrated with the GRID through a reverse metering system, enabling excess energy to be sold back to the GRID. This research underscores the significance of transitioning to renewable energy sources in industries for environmental sustainability, energy security, and economic benefits. It emphasizes the need for similar studies in diverse industrial settings to identify the most suitable energy sources, considering all relevant factors.

Integrated development strategy of industrial buildings and farming communities in Hong Kong

Insufficient agricultural land and a high vacancy rate in industrial buildings are important problems facing Hong Kong. Therefore, this study aims to determine whether industrial buildings are suitable as agricultural spaces and to formulate corresponding utilization strategies to promote agricultural production and food supply in Hong Kong. Research objects include industrial building space and hydroponic agricultural space. This paper used literature research and field research as the main research tools to collect relevant information on the utilization potential of industrial buildings and hydroponic agriculture. In addition, research data are derived from literature studies and surveying data, which provide detailed information about the industrial building structure and surrounding environment to better assess its suitability and feasibility. This research concludes that industrial buildings are potentially suitable for use in agricultural spaces, especially hydroponic agriculture. Its internal structure and environmental conditions can support agricultural production and effectively use vacant industrial building space to expand the scale of agricultural production. Regarding utilization strategies, this study recommends using recycling systems and related technologies, such as hydroponic systems and LED lighting, to transform industrial buildings internally to create farming communities. This will help make agricultural production more efficient and sustainable while providing cities with a fresh supply of produce.

Enhancing Water-Sensitive Urban Design in Chiang Mai through a Research–Design Collaboration

Water-sensitive urban design (WSUD) is a subset of nature-based solutions (NbSs) that are implemented worldwide. However, the WSUD guidelines in some local contexts, such as Southeast Asia, remain unclear both for ecological and cultural reasons. This study aims to gather collaborations between researchers, designers, and laypeople in WSUD, which have the potential to be implemented to address water quality issues. The study consisted of three stages: site selection, a design workshop, and public interviews. Utilizing geo-design principles and geographical data, the potential pilot site was identified: a vacant space next to the Tha Phae Gate Plaza. A two-day workshop with landscape design experts yielded six conceptual designs, focusing on diverse themes such as water treatment, plant-based solutions, educational opportunities, and cultural enrichment. Public interviews provided insights into the community’s perspectives on stormwater management, desired amenities, environmental considerations, and governance concerns. The results highlighted a collective interest in using NbSs for stormwater treatment and enhancing the area’s recreational and educational potential. This study offers a comprehensive approach to addressing water quality issues in urban settings while considering local cultural, recreational, and environmental needs.

Occupations as reparative urban infrastructure: thinking with Cissie Gool House

Understood as a direct claiming and remaking of vacant space by marginalized urban residents, occupations claim the right to housing and disrupt property relations, surfacing conflicting rationalities between different valorizations of land and infrastructure. We are interested in occupation as a reparative practice, intervening into the socio-material fabric of the city, with the potential to remake urban life-worlds. We draw inspiration from scholarship on infrastructural repair, conceived as the necessary labor of sustaining and filling in the gaps of fragile systems of provisioning that would otherwise be abandoned or left to decay. We situate our reflection in Cape Town, at the Cissie Gool House occupation, a former hospital that was vacant when it was occupied in 2017. In paying attention to the labors of endurance at CGH, this paper advances an expanded conceptual framework of repair, conceiving of occupations as a reparative urban infrastructure that includes material and affective practices. Our concern is with the enactment of more emancipatory forms of reparative practices that prefigure more hopeful futures. In thinking with CGH, we draw out a set of practices that can be read as central to sustaining, reclaiming, and future-making, naming these: infrastructural repair, prefiguration, defiant endurance, and refusal.

Hop, Skip, and Jump: Hydrogen Molecular Transport through Amorphous Polyethylene Matrices Studied via Molecular Dynamics Simulations.

In the pursuit of advancing and diversifying energy technologies for a more sustainable future, the possibilities of hydrogen (H2) usage will broaden, as will our understanding of its containment materials. Polyethylene (PE) has a vast assortment of uses and applications, which are growing with demands for alternative energy possibilities. One use of PE liner is as a prime candidate for nonmetallic piping and pressurized type IV storage devices. Such applications require PE to effectively prevent H2 transport through containment systems. To study the molecular transport mechanism of hydrogen through polymeric barriers, a system containing hydrogen molecules absorbed within amorphous PE is modeled here using molecular dynamics simulations. The simulations are conducted within a range of temperatures that span the glass transition temperature of amorphous PE. The simulated PE displays bulk density, radius of gyration, and self-diffusion coefficient that are consistent with experimental data. The simulated trajectories are interrogated to study the movement of the guest gas molecules. The results show that the diffusion coefficients increase with temperature, as expected. However, the mobility of the PE chains is found to affect the mobility of absorbed H2 molecules to a much lower extent than it affects that of CH4 molecules because of the much smaller size of the former than of the latter guest. From a molecular perspective, a "hopping" mechanism is observed, according to which H2 molecules hop between one vacant free volume space to another within the polymer matrix, in combination with longer, straight, undisturbed "jumps" or "skips" along directions aligned with regions of ordered PE chains. This suggests that the orientation of the crystallites within the semicrystalline PE matrix affects the H2 containment. Implications of these findings toward PE usage as containment material are discussed.

The rising threat of peyssonnelioid algal crusts on coral reefs

For more than a century, coral reefs have been exposed to increasing anthropogenic disturbances that have profoundly altered their community structure. These perturbations continue to challenge coral reefs in new ways as ecological paradigms are recast in the Anthropocene Epoch1. In recent decades, macroalgal blooms have blighted Caribbean reefs2, but the appearance of aggressive peyssonnelioid algal crusts (PAC) that are rapidly increasing in abundance to become dominant members of the benthos on Caribbean and Indo-Pacific reefs is a novel phenomenon in tropical seas3. By pre-empting vacant space, overgrowing corals, deterring the settlement of coral larvae, and favouring a phase transition from coral to algae4, PAC are likely to accelerate the decline in dominance of corals on global reefs (Figure 1).

Evaluation of the influence of surface structure on tribological properties of the solid–liquid interface: Analytical and experimental assessment

Nowadays, multiple strategies have been suggested to improve product efficiency on the basis of risk free techniques. Owing to the vast applications of the structured surface in many industrial sectors, considerable attention has been paid by many scholars to improve the surface performance aspects by studying their solid–liquid interface characterizations. In the current study, a new technique is introduced to manufacture a functional surface with water repellency feature through grinding process. Based on the solid–liquid interface evaluations of the modified surface, by structuring the surface, the contact angle increases from 35° (untreated surface) to 127° for structured surface. Therefore, the reinforced surface showed hydrophobicity with a 263% improvement for a scratch area fraction more than 75%. Formation of air pads trapped in the vacant space of the scratches was the main cause to enhance contact angle for structured surface. Since air molecules have very low inclination to chemical bonding with water molecules, the water droplet did not penetrate the scratches space and contact angle enhanced. A new analytical model for predicting the solid–liquid surface property was simultaneously developed by interaction of the kinematics of the grinding technique with single diamond and the basic wettability theory of the Cassie-Baxter. Therefore, the effect of all input parameters on the output results was studied in terms of achieving the best solid–liquid interaction performance through expanded model. The optimal values were calculated and the proposed structured surface was manufactured during the grinding process. According to the value of the static contact angle measured during experimental tests (127°) and its analytical value (123°), less than 4% error was observed between the results, which showed the high accuracy of the equation expanded on the present work.

Smart Parking System Using IoT

Abstract: Finding the car parking place in huge parking lot is a major issue and it consumes lot of time. In this regard, this project is designed to detect the vacant place and information will be sent to the organizer of the parking place through his mobile phone by which the person can guide the driver of incoming vehicle. The organizer or coordinator often will be sat at the entrance of parking lot by which he can guide accordingly. The system displays about the details of freed-up parking spaces through an LCD interfaced with Arduino board and the same information will be transmitted to the concern mobile phone through Wi-Fi module. This helps the motorists to cut time to park their vehicles. The waiting time to park the vehicle can be reduced by providing this vacant space information to the motorists before he/she enters the parking lot. The system recognizes the vacant space and displays the information automatically. To sense the vehicle at parking place, infrared sensors are used and the output of the sensors is fed to the Arduino microcontroller and according to the received information from the sensors, the controller displays, that the particular parking place is vacant or full. For the demonstration purpose three sets of sensors are used to simulate three parking sites. But for real time applications, the same system with required modifications can be used to find hundreds of parking slots and each and every parking place can be identified weather it is full or empty. In this prototype model, the system is designed such that, when all parking sites are filled and there is no space for another vehicle, automatically the gate will be closed. To simulate the gate a small barrier of 10” is used and it is attached to the DC motor shaft. If any vehicle is removed from its slot, automatically, the gate will be opened to allow another incoming car.