Low Floor Research Articles

Community exoplanet imaging data challenge for Roman CGI and starshade rendezvous

Operating in an unprecedented contrast regime (10 − 7 to 10 − 9), the Roman Coronagraph Instrument (CGI) will serve as a pathfinder for key technologies needed for future Earth-finding missions such as HabEx and LUVOIR. The Roman Exoplanet Imaging Data Challenge (Roman EIDC) was a community engagement effort that tasked participants with extracting exoplanets and their orbits for a 47-UMa-like target star given: (1) 15 years of simulated precursor radial velocity (RV) data and (2) six epochs of simulated imaging taken over the course of the Roman mission. Led by the Turnbull CGI Science Investigation Team, the Roman EIDC was preceded by four tutorial “hack-a-thon” events in Baltimore, Pasadena, New York City, and Tokyo. The Roman EIDC officially launched in October 2019 and ran for 8 months, offering a unique opportunity for exoplanet scientists of all experience levels to get acquainted with realistic near-future imaging data. The Roman EIDC simulated images include four epochs with CGI’s Hybrid Lyot Coronagraph (HLC) plus two epochs with a starshade (SS) assumed to arrive as part of a Starshade Rendezvous later in the mission. We focus on our in-house analysis of the outermost planet “d,” for which the SS’s higher throughput and lower noise floor present a factor of ∼4 improvement in the signal-to-noise ratio over the narrow-field HLC. We find that, although the RV detection was marginal for planet d, the precursor RV data enabled the mass and orbit to be constrained with only two epochs of SS imaging. Including the HLC images in the analysis results in improved measurements over RV + SS alone, with the greatest gains resulting from images taken at epochs near maximum elongation. Combining the two epochs of SS imaging with the RV + HLC data resulted in a factor of ∼2 better orbit and mass determinations over RV + HLC alone. In summary, the Roman CGI, combined with precursor RV data and latermission SS imaging, forms a powerful trifecta in detecting exoplanets and determining their masses, albedos, and system configurations. While the Roman CGI will break new scientific and technological ground with direct imaging of giant exoplanets within ∼5 AU of V ˜ 5 and brighter stars, a Roman Starshade Rendezvous mission would additionally enable the detection of planets out to ∼8 AU in those systems.

Preoperative Evaluation of the Lower Extremity-Specific PROMIS Mobility Bank in Patients with ACL Tears

PurposeThe purpose of this study was to preoperatively assess the Patient-Reported Outcomes Measurement Information System (PROMIS) Item Bank v2.0–Mobility in patients with anterior cruciate ligament (ACL) tears to (1) determine construct validity by correlating with legacy patient-reported outcomes (PROs), (2) evaluate test burden, (3) determine the presence of floor or ceiling effects, and (4) revisit the conventional threshold for inclusiveness (floor/ceiling effects) in the modern era of computer adaptive testing (CAT)–based PROs.MethodsPatients at a large academic musculoskeletal specialty center diagnosed with ACL tears indicated for surgery were administered the following outcomes measures before surgery: PROMIS Mobility CAT, PROMIS Pain Interference CAT (PROMIS PI), International Knee Documentation Committee (IKDC), the Marx Knee Activity Rating Scale (Marx), and Single Assessment Numeric Evaluation (SANE). Construct validity was evaluated using Spearman correlation coefficients. Correlation strengths were defined as high (≥0.7), high-moderate (0.61-0.69), moderate (0.4-0.6), moderate-weak (0.31-0.39) and weak (≤0.3). Number of questions to completion were recorded as a marker of test burden. The percentage of patients scoring at the extreme high (ceiling) or low (floor) of each measure was recorded to measure inclusivity.ResultsA total of 1126 patients were evaluated. The mean number of questions answered (± standard deviation) was 4.7 ± 2.1 for PROMIS Mobility and 4.5 ± 1.9 for PROMIS PI. PROMIS Mobility demonstrated a high correlation with IKDC, (r = 0.81, P < .001), a high-moderate correlation with PROMIS PI (r = −0.63), and a moderate correlation with SANE (r = 0.46, P < .01). Neither PROMIS Mobility nor PROMIS PI met conventional criteria for floor or ceiling effects (>15%).ConclusionsThe PROMIS Mobility measure maintains construct validity, because its scores correlate strongly with other PROs measuring physical function with high efficiency among preoperative patients with ACL injuries. Although ceiling effects of PROMIS Mobility CAT were below the conventional significance threshold of 15% at the preoperative timepoint in this population, this study provides critical feedback for redesigning the Mobility bank.Level of EvidenceLevel III (Diagnostic study).

The influence of airtightness on contaminant spread in MURBs in cold climates.

Tall buildings in cold climates have unique challenges in maintaining indoor air quality due to stack effect. During the heating season, interior air buoyancy creates large pressure differentials in vertical shafts that can drive airflow from lower floors into upper floors. This pressure differential can result in the spread of contaminants throughout a building. Most recently, concern over COVID-19 has increased attention to the potential spread of airborne diseases in densely populated buildings. For many multi-unit residential buildings, suite ventilation has traditionally relied upon fresh air supplied through a mechanically pressurized corridor. In cold climates, large pressure differentials created by stack-effect can reduce the effectiveness of this approach. Multizone and CFD simulations are employed to analyze airflow and contaminant spread due to stack effect. Simulations are conducted on an idealized model of a 10-storey building using a range of experimentally derived airtightness parameters. Simulations demonstrate stack effect can reduce corridor ventilation to suites and even reverse the airflow for leakier buildings. Reduced airflow to suites can result in the accumulation of contaminants. Reversal of the airflow can allow contaminants from a suite to spread throughout the building. Contaminant spread is illustrated as a function of mechanical ventilation, building airtightness, and ambient temperatures. Strategies to reduce the influence of stack effect on mechanically pressurized corridors are discussed.

Error correction in data storage systems using polar codes

This paper investigates error correction in two-dimensional (2-D) intersymbol interference (ISI) channels using polar codes. 2-D channels offer high data storage capacity compared to traditional one-dimensional (1-D) channels but suffer from greater ISI effects. Error correction codes can be used to mitigate the effects of ISI in 2-D data storage systems and improve their performance and reliability. Polar codes achieve the symmetric capacity for the class of binary-input discrete memoryless channels (B-DMCs). A post-processing technique is proposed to improve the performance of polar codes in the 2-D ISI channel. The simplified successive cancellation (SSC) polar decoder is useful for data storage systems owing to its good waterfall region performance, low error floors and good throughput rates and is therefore adopted for the study. Simulation results indicate that the proposed technique has an error correction performance comparable to some existing decoders and has better performance than other decoding techniques.

Effects of different feeder and floor space allowances on growth performance and welfare aspects in nursery pigs

Due to increasing litter size at weaning, the stocking density in the nursery phase has increased and feeder space reduced. Understanding how both factors work is potentially relevant to reduce the negative implications for piglet growth performance and welfare. A 3 × 4 factorial arrangement with 2160 pigs was used in a 42-day study to investigate the effects of floor space allowance (0.15, 0.25, and 0.35 m2/pig) and feeder space (1.6, 3.2, 4.8, and 6.4 cm/pig) on growth performance, and tail and ear lesions in nursery pigs at a commercial farm. Pen dimension provided 0.35 m2/pig, and divider fences were used to provide 0.15 and 0.25 m2/pig, with 20 pigs per pen for all treatments. More pigs were removed in 0.15 than 0.25 and 0.35 m2/pig (P < 0.01), and with 1.6 cm/pig than 4.8 and 6.4 cm/pig (P < 0.05). The occurrence of ear lesions was higher with 0.15 m2/pig or 1.6 cm/pig than with higher floor or feeder spaces (P < 0.05). Tail lesion occurrence was affected by the interaction between floor and feeder spaces (P < 0.05), i.e., minimized by an increased feeder space when floor space was limited or increasing floor space when feeder space was limited. Increasing the floor space allowance linearly increased the average daily feed intake (P < 0.01). The overall gain:feed increased as feeder space increased from 1.6 to 3.2 cm/pig, after which there was a plateau (P < 0.05). The optimal responses for ADG, mean body weight (BW) at 42 days, and final pen weight (> 380 g/day, > 22.5 kg, and > 440 kg, respectively) were obtained with floor space ranging from 0.25 to 0.35 m2/pig, and feeder space from 4.0 to 4.4 cm/pig. Furthermore, low ADG (< 360 g/day), mean BW (< 22 kg), and final pen weight (< 420 kg) were obtained when low floor space was combined with low feeder space (0.15 m2/pig combined with 1.6 and 3.2 cm/pig, or 0.25 m2/pig with 1.6 cm/pig). When 0.15 m2/pig was used, the CV of BW was reduced in feeder spaces of 4.8 and 6.4 cm/pig, contrasting with little variation in pigs provided with 0.35 m2/pig. In conclusion, feeder and space allowance affected nursery pig performance mostly in an interrelated way. An increase in feeder space allowance can, to some extent, mitigate the negative effect of restricted floor space allowance on growth performance and the occurrence of tail lesions.

Oil Slick Discrimination and Characterization: A Multisource Image Processing System to Integrate SAR &amp; PolSAR Data during Emergency Responses

ABSTRACT 1141194 During oil spills response activities (OSR), discrimination and characterization of oil slicks has the potential to minimize false alarms and to indicate the location of thicker layers of oil, providing tactical and strategic information to decision makers. This specific demand for spatial intelligence during emergencies emphasizes the importance of the Multisource Image Processing System developed by the Brazilian Institute for Space Research (INPE) and described herein. Synthetic Aperture Radars (SAR) are the most common operational remote sensing data providers, acquiring images in different frequencies, incidence angles, resolutions, polarizations and formats (amplitude, intensity or complex). The system is able to integrate this product diversity including polarized (SAR), polarimetric (PolSAR) and optical data acquired by multiple sensors with different signal to noise ratios (SNR) and statistical distributions. The classifier uses a supervised approach to compare stochastic distances between different statistical distributions and statistical hypothesis testing to associate confidence levels to the results. Two study cases including mineral and biogenic oils with internal thickness variations were used to demonstrate the potential of the system to process SAR and PolSAR data, considering different formats and statistical distributions. The system was able to differentiate mineral oils from biogenic oils, as well as to detect thicker layers within the oil slicks with high global accuracies and low uncertainties. The polarimetric (dual and full-pol) and the intensity pair data had better accuracy at discriminating different types of oils; meanwhile SAR and PolSAR data returned statistically equivalent global accuracies in characterizing oil slicks. The low noise floor in UAVSAR sensor is able to detect oil thickness variations, which is feasible even if only using the VV channel. The possibility to qualitatively identify the thicker layers of the spilled oil, as well as minimize false alarms ratio is a significant contribution to ongoing efforts to improve OSR. The classification maps provided by the system may also be used to extract the relative areas for each type of oil, supporting the oil volume estimation. In this context, the integration of all information extracted from SAR and PolSAR data is useful both at strategic and tactical levels of an emergency, and is being used to guide aerial surveillance and the deployment of barriers and skimmers, aiming to increase oil recovery efficiency and minimize environmental impact.

Ancestry-based variation in maxillary sinus anatomy: Implications for health disparities in sinonasal disease.

Paranasal sinus drainage is mediated by mucociliary transport and gravity. However, human orthograde posture, along with the superior positioning of the maxillary sinus (MS) ostium, increases reliance on the mucociliary system. Previous research has thus suggested that differences in MS size and shape may impede mucociliary clearance, potentially contributing to disparities in sinusitis susceptibility. To further investigate this hypothesis, this study collected 29 three-dimensional (3D) coordinate landmarks and seven linear measurements of MS morphology from 167 computed tomography (CT) scans of crania of European, East Asian, or Equatorial African ancestry. MANOVA results reveal the Asian-derived individuals are characterized by both a significantly taller MS (F=14.15, p < 0.0001) and a significantly greater distance from the MS floor to the ostium (F=17.22, p < 0.0001) compared to those of European and African ancestry. A canonical variate (CV) analysis conducted on 3D landmark data provides corroborative results, distinguishing Asian-derived individuals predominantly on the basis of a relatively lower MS floor. As a greater distance between the MS floor and ostium may impede mucociliary clearance, our results suggest MS anatomy may be a more prominent factor in chronic sinusitis among individuals of Asian ancestry compared to those of European and African ancestries. This provides tentative evidence of an anatomical etiology for chronic sinusitis even in the absence of anatomical variants/abnormalities (e.g., nasal polyps, concha bullosa, Haller's cells, and Agger nasi cells). Further research into the relationship between MS anatomy and sinusitis, in addition to socioeconomic inequalities of healthcare, is warranted to continue evaluating possible contributions to health disparities.

The Performance of Secondary Nasal Alar Base Revision for Unilateral Cleft Lip by Single YV-Plasty (the Importance of Overcorrection During Surgery).

Although primary surgery for cleft lip has improved over time, the degree of secondary cleft or nasal deformity reportedly varies from a minimum degree to a remarkable degree. Patients with cleft often worry about residual nose deformity, such as a displaced columella, a broad nasal floor, and a deviation of the alar base on the cleft side. Some of the factors that occur in association with secondary cleft or nasal deformity include a deviation of the anterior nasal spine, a deflected septum, a deficiency of the orbicularis muscle, and a lack of bone underlying the nose. Secondary cleft and nasal deformity can result from incomplete muscle repair at the primary cleft operation. Therefore, surgeons should manage patients individually and deal with various deformities by performing appropriate surgery on a case-by-case basis. In this report, we applied the simple method of single VY-plasty on the nasal floor to a patient with unilateral cleft to revise the alar base on the cleft side. We adopted this approach to achieve overcorrection on the cleft side during surgery, which helped maintain the appropriate position of the alar base and ultimately balanced the nose foramen at 13 months after the operation. It was also possible to complement the height of the nasal floor without a bone graft. We believe that this approach will prove useful for managing cases with a broad and low nasal floor, thereby enabling the reconstruction of a well-balanced nose.

Clinical and Epidemiological Profile of Oral and Maxillofacial Trauma at Two Quaternary Hospitals in Mozambique in 2016

Background: Our objective was to evaluate the clinical and epidemiological profile of maxillofacial trauma in patients attended to at the Maputo Central and Nampula Central hospitals in 2016.&#x0D; Methods: A descriptive cross-sectional retrospective study based on clinical records of all patients with maxillofacial trauma who attended consultations or were admitted to wards of the maxillofacial surgery services from January to December 2016. Statistical tests looking for significance levels of 5% were performed in SPSS.&#x0D; Results: Trauma accounted for 482 (35.65%) patients treated at the central hospitals of Maputo and Nampula: of these patients 373 (77.4%) fell in the 15–44-year age group, 363 (75.31%) were male, and 430 (89.21%) were ethnically African. Most patients (259 or 53.77%) treated at these hospitals were outpatients. The most frequent cause of trauma (albeit without statistical significance) wasphysical violence. The lower floor of the face was more frequently involved (279 or 57.88%), and the most common treatment was closed reduction (238 or 49.38%).&#x0D; Conclusion: The characteristic clinical and epidemiological profile of patients with maxillofacial trauma is mainly fractures of the lower floor of the face. These types of injuries are usually severe, and developing preventative and multidisciplinary conducts and treatment protocols for these patients is imperative.&#x0D; Keywords: Epidemiological profile, Maxillofacial trauma, Mozambique

이미지시스템을 이용한 반복하중조건에서 압착식 조인트가 적용된 입상배관의 거동분석

In the event of an earthquake, structures are shaken in various ways, resulting in side-sway between stories of a structure. When side-sway occurs in a building due to an earthquake, the facilities installed in the building are also affected. In particular, the facilities that connect a lower floor to a higher floor, such as riser pipes, are significantly affected by sidesway. In this study, a steel frame realizing the second floor of a structure was fabricated, and a riser pipe with pressure joints was installed in accordance with NFPA 13. Moreover, the seismic behavior of the riser pipe was analyzed by conducting cyclic loading tests on the maximum allowable amount of sidesway. Furthermore, the deformation angle, strain, and stress required to assess the seismic performance of the fittings and joints of the riser pipe in the event of a seismic load were also analyzed.

Performance analysis of short length low density parity check codes

Outstanding bit error rate LDPC design in waterfall region and error floor region is one of the challenging tasks for the past decade. This chapter, focuses on the design of LDPC encoder with the low error floor and waterfall region of BER with minimum trapping set. Scheduled Progressive Edge-Growth (SPEG) LDPC encoder is used, and the simulation result of density evolution and exit chart are giving the better convergence of LDPC encoder. BER performance in error floor can controlled by minimum trapping set and waterfall region controlled by scheduled PEG LDPC encoder (1000, 500) with code length (n) is less than 600. The girth of the SPEG encoder is 8. SPEG with minimum trapping set will perform well for short length code also and it converges faster than the other PEG encoder.

Natural ventilation for office building retrofit in dense urban context under hot and humid climate

Abstract Recent studies underline that simple and non-invasive retrofit solutions can recover natural ventilation potential in existing buildings under temperate climate. Nonetheless, the efficiency of these solutions in dense urban contexts under hot and humid climate remains unclear. This paper aims to evaluate the thermal comfort gains caused by natural ventilation when retrofitting an office building in downtown Rio de Janeiro. Computational Fluid Dynamics (CFD) and thermal simulations are carried out on Ansys CFX and Design builder to assess indoor air flow before and after retrofit. The diagnosis of the current scenario indicates that the surrounding buildings block a significant part of the wind flow, and occupants experience only a few hours of thermal comfort during the year, especially on lower floors. To increase indoor air flow, the fixed upper windows were transformed into pivot windows and kept open permanently. This measure increases the annual hours of thermal comfort by 0.5-35%, depending on the floor and the adaptive comfort model. These findings suggest that natural ventilation itself may not be sufficient to ensure occupants' comfort throughout the year under the investigated context.

Анализ современных технических решений, применяемых в конструкциях низкопольных трамвайных вагонов

Objective: To show the prospects of using public urban transport and, first of all, high-capacity light rail rolling stock for urban transportation, and in the immediate future, the possibility of completely abandoning private vehicles for movement around the city. As a result, this will help lessen the traffic jam load in Russian megacities. Methods: The authors have analyzed and applied best practice of the leading tram companies in Europe (Vienna, Prague, Riga, etc.), analyzed the most progressive designs of the rolling stock and their undercarriage, and compared foreign and domestic experience of service facilities operation. Results: The experience of many European companies has proved the feasibility of using cars with swivel bogies, which have a beneficial effect on the track and make it possible to pass curves of small radii. The use of wagons made of multi-link structures allowed designing a completely low-floor cabin. It is advisable to place a gearbox and an electric drive on the outside of the low-floor car undercarriage, or to use a gearless drive and low-speed electric motors. Practical importance: The introduction of low-floor cars in cities improves the accessibility of this type of transport for passengers, primarily for passengers with disabilities, and significantly reduces the time of their boarding (disembarking). The advantage of cars with swivel bogies is shown. The increased complexity of the undercarriage design allows designers to create an extremely low floor cabin, but this consequently leads to an increase in the cost of rolling stock, an increase in repair costs, stricter requirements for the support services and a demand for highly qualified technical personnel. It is recommended to purchase domestic low-floor rolling stock as the most adapted to operation in Russian cities.

Development and Validation of a Perceived Barriers to Physical Activity Scale for Low-Income Adolescents.

Low-income adolescents' physical activity (PA) levels fall below current recommendations. Perceived barriers to physical activity (PBPA) are likely significant predictors of PA levels; however, valid and reliable measures to assess PA barriers are lacking. This manuscript describes the development of the PBPA Survey for Low-Income Adolescents. A mixed-method approach was used. Items identified from the literature and revised for clarity and appropriateness (postcognitive interviews) were assessed for test-retest reliability with 74 adolescents using intraclass correlation coefficient. Items demonstrating low intraclass correlation coefficients or floor effects were removed. Both exploratory factor analysis and confirmatory factor analysis analyses (n = 1914 low-income teens) were used to finalize the scale; internal consistency was assessed by Cronbach's alpha. Concurrent validity was established by correlating the PBPA with the PA questionnaire for adolescents using a Spearman correlation. The exploratory factor analysis yielded a 38-item, 7-factor solution, which was cross-validated by confirmatory factor analysis (comparative-fit index, nonnormed fit index = .90). The scale's Cronbach's alpha was .94, with subscales ranging from .70 to .88. The PBPA Survey for Low-Income Adolescents' concurrent validity was supported by a negative PA questionnaire for adolescents' correlation values. The PBPA Survey for Low-Income Adolescents can be used to better understand the relationship between PBPA among low-income teens. Further research is warranted to validate the scale with other adolescent subgroups.

Structural Response of Steel Jacket-UHPC Retrofitted Reinforced Concrete Columns under Blast Loading.

The lateral capacity of exterior concrete columns subjected to a blast load is the key factor in the building collapse probability. Due to potentially severe consequences of the collapse, efforts have been made to improve the blast resistance of existing structures. One of the successful approaches is the use of ultra-high-performance-concrete (UHPC) jacketing for retrofitting a building’s columns. The columns on the first floor of a building normally have higher slenderness due to the higher first story. Since an explosion is more likely to take place at the ground level, retrofitting the columns of the lower floors is crucial to improve a building’s blast resistance. Casting a UHPC tube around a circular RC column can increase the moment of inertia of the column and improve the flexural strength. In this study, a retrofitting system consisting of a UHPC layer enclosed by a thin steel jacket is proposed to improve the blast resistance of buildings in service. Most of the previous research is focused on design aspects of blast-resistant columns and retrofitting systems are mostly based on fiber reinforced polymers or steel jackets. A validated FE model is used to investigate the effectiveness of this method. The results showed significant improvement both at the component and building system levels against combined gravity and blast loading.

A sensitive micromachined resonant accelerometer for moving-base gravimetry

A sensitive micromachined resonant accelerometer that exhibits extremely low noise floor and excellent bias stability is presented for future application of moving-base gravimetry. An overall structure optimization is presented for large scale factor and low noise, which is significant for measuring variations in the gravitational field of the Earth. The experimental results show that the MEMS accelerometer has a scale factor up to 876 Hz/g and a noise floor down to 75ng/Hz by setting a relatively low full-scale range of ±5 g. The experimental results of the resonant accelerometer with ±0.01°C temperature control show that the averaged bias stability for one day duration is 0.197 μg and the bias repeatability within about 3 months is 1.56 μg. Furthermore, a six-day measurement duration of the accelerometer with its sensitive axis perpendicular to the ground shows a sensitive measurement synchronously with the Earth's tidal gravity, which demonstrates that the resonant accelerometer has the capability for high-performance applications such as moving-base gravimeters and shipborne inertial navigation systems.

Avifauna of the Adelbert Mountains, New Guinea: why is Fire-maned Bowerbird Sericulus bakeri the mountains' only endemic bird species?

The Adelbert Mountains, one of ten outlying ranges along New Guinea's north and north-west coasts, surprised ornithologists when their first exploration by Western scientists yielded the striking endemic Fire-maned Bowerbird Sericulus bakeri. It was then another surprise when further exploration revealed no other distinctive endemic. We summarise previous Adelbert studies and our four explorations including a survey of the highest summit. A total of 71 upland species has been recorded from the Adelberts, all of them also present as the same species or (in the case of S. bakeri) same superspecies on other outliers. The Adelberts are exceptional among low-elevation outliers in harbouring populations of seven upland species shared only with much higher outliers. The Adelberts are unique in supporting populations of ten upland species compressed at the highest elevations into a narrow elevational band below the summit. The elevational floors of those species lie a much shorter distance below the summit than for any species on any other outlier. In explanation, we propose the hypothesis that, among outliers, the Adelberts are especially accessible to colonisation by upland species from other upland areas, with two consequences: endemism is almost non-existent in the Adelberts except S. bakeri; and high-elevation populations of the Adelberts may be subsidised by colonists from other upland areas. The highest-elevation populations may have disappeared during the mid-Holocene hypsithermal and subsequently recolonised, further contributing to the lack of endemism. The Adelbert upland avifauna is more closely related, in presence / absence and taxonomic relationships, to that of the nearby Huon Mts. to the east than to the avifauna of the more distant North Coastal Range to the west. That suggests why the Adelberts support S. bakeri as such a distinctive endemic but the rest of their avifauna is undifferentiated: Sericulus is the only upland superspecies of north New Guinea that reaches its eastern distributional limit in the Adelberts; and its low elevational floor permitted it, but not higher-elevation species, to survive upwards shifts in range during the hypsithermal. An appendix summarises all 235 species recorded from the Adelberts, our observations of their elevational range and abundance, and their names in two local mountain languages of the Adelberts.

Strata movement and fracture evolution characteristics in adjacent seam mining

The mining-induced stress distribution and fracture characteristics of overlying strata in the lower coal seams are different from those in single coal seam mining. Based on the distribution of the mining-induced fracture elliptical parabolic zone in a single coal seam, the dynamic distribution equation is deduced for the mining-induced fracture elliptical parabolic zone in two short coal seams through theoretical analysis. Combined with physical experiment and numerical simulation, a study has been made on the characteristics of overlying strata deformation, displacement, and mining-induced fracture evolution in the single coal seam and its lower coal seam mining. The results show that high stress concentrations occurred near the coal pillars at the upper coal floor on both sides after mining, and the overlying strata subsidence of the upper coal seam is 155.70% of the intermediate strata after superimposed mining, with the upper and lower coal floor showing significant stress relief. Under the influence of the two mining actions, the overlying strata of the upper coal seam have more fully developed fractures. The fracture density increases with the advance distance, the position of caving zone and fracture zone continues to develop upward, and the compaction zone further compacts; the fracture zone presents the distribution of the superimposed mining elliptical paraboloid zone. FLAC3D was used to simulate superposition of two layers of coal mining; the strata displacement and stress distribution nephograms were obtained as well, with the result that the floor stress release could reach up to 14.87 MPa under the influence of mining of two adjacent seams. This indicates that the pressure relief degree of the floor under the influence of two mining operations is obviously higher than that under one mining operation. The fracture distribution obtained by numerical simulation is basically consistent with the physical simulation and the superimposed mining elliptical paraboloid zone.

Principles of Formation of Aboveground Parking Lots as a Part of Residential Building or Complex

The article deals with the problem of parking and storage of personal transport in multi-storey residential development areas. Using of underground parking under a building or yard may not always be the most profitable solution. Especially taking into account that the nature of the soil in the largest megacities of Russia is very complex and it leads to a strong increase in the cost price of the project. Options for organizing above-ground parking are proposed and analyzed. The advantages and disadvantages of modern free-standing parking lots are described in the article. Examples of built-in attached parking lots within a residential group are demonstrated too. The advantages of automated parking lots built into the lower floors of high-rise buildings are listed. Project proposals are presented that demonstrate the possibility of placing automatic Parking directly in the lower floors of a residential building.

The effects of dynamic pressure on the stability of prepared drifts near the working surface areas

Due to the effects of dynamic pressure, the stress distribution of rock mass is very complex. The reason for this could be a risk of stability loss for an auxiliary tunnel system constructed within the study area. In this article by using Flac3D software the author simulated two adjacent working faces with the thickness of 5 m natural coal pillar. Three factors: the upper working face excavation process, auxiliary tunnel mining process, and the location of lower working face, affected by deformation, stress distribution, safety of lower floor area and surrounding rock mass of tunnel. The research results show that during the excavation, the mechanical behavior of the rock mass surrounding the auxiliary tunnel showed displacements, volatility, and phase characteristic. The displacement on the auxiliary tunnel boundary in both excavation and working face cases showed that the roof and the left side wall displacement was greater than the right side wall and the bottom. Therefore, the distance between the auxiliary tunnel and the empty mining space needs to be computed to meet technical and economic requirements.