Tunnel Type Research Articles

How To Identify The Quality Figs?

Fig production is carried out in a very limited number of countries in the world, and accordingly, the number of countries producing dried figs is quite low. In this study, a small scale tunnel type greenhouse model dryer was designed and manufactured. In this study, the process of drying figs with hot air was carried out by using a combination of uninsulated greenhouse and collector system. Sarılop fig variety was chosen as the food to be dried. The experiments were carried out in Aydın in August 2021. Drying parameters were determined for figs. In addition, the figs offered to the market throughout the province were examined, the practices that should be done to prevent drying damage in figs were determined, and the answer to the question of how to understand quality figs was sought. In the preparation of the study, the studies of the provincial directorate of agriculture, TÜİK reports, visual and printed documents were also examined.

Design and Manufacturing of Wind Tunnel for Turbine Impeller Airfoil Testing

In this study, the design of a wind tunnel was carried out to observe airflow through an airfoil, streamlines and turbine blades. To accommodate this, in this study a design was made of an open return wind tunnel. In this case, an open circuit wind tunnel type will be made because the construction is simpler and the manufacturing costs are relatively cheaper compared to the closed circuit wind tunnel type. The Wind Tunnel is designed with Open CLosed Wind Tunnel (OCWT) type. The OCWT is designed to consist of fan and housing, diffuser, test section, contraction, honeycomb. The OCWT design uses an operating fan to circulate air into the test section. The maximum air speed in the Test Section is 5 m/s with a flow that is closed to laminar. The recommended diffuser has a dimension of 50 cm on the side that is attached to the test section and 52 cm on the side facing the fan with an inclination angle of 1.79o. The driver uses a 16 inch exhaust fan with a power of 74 W to make the flow in the Test Section stable at a speed of 2 m/s.

Research on the Safety Thickness of Tunnel Outburst Prevention in Water-Rich Fault Fracture Zone Based on Janssen’s Theory

In the construction of tunnel in water-rich fault fracture zone, when the thickness of outburst prevention is insufficient, it is very easy to cause water and mud inrush engineering accident. Therefore, it is very necessary to study the safety thickness of outburst prevention for this type of tunnel. In this paper, the expression of in situ stress in water-rich fault fracture zone is derived based on Janssen’s theory. Two mechanical models of outburst prevention rock mass are established, and according to the shear balance theory, the calculation formula for the safe thickness of outburst prevention is determined and the parameter sensitivity analysis is carried out. Finally, it is verified by engineering examples and numerical simulation. The results show that: (1) the calculation formula of outburst prevention thickness proposed in this paper is more perfect and shows good prediction effect for deep- and shallow-buried tunnels; (2) the greater the angle α between tunnel axis and fault zone and the dip θ of fault fracture zone, the smaller the critical safety thickness of outburst prevention and the safer it is for tunnel construction; (3) when the fault fracture zone inclines inward relative to the tunnel face, the gravity of the rock mass in the fault zone will lead to an increase in the safety thickness of outburst prevention, and reinforcement measures should be taken during actual construction.

Review on Tunnel Communication Technology

Tunnels account for an increasing proportion of highways. Due to the semi-closed structure of tunnels, signal communication is difficult in tunnels. This review analyzes the signal data transmission requirements of intelligent network management systems, such as lighting systems, wind protection systems, fire protection systems, and vehicle and pedestrian positioning systems in tunnels. The selection of signal coverage and transmission methods are also discussed. The advantages and disadvantages of various networking methods are analyzed. This paper summarizes the wireless signal transmission, wired signal transmission and signal transmission modes of different tunnel types.

FEM-Based Analysis of the Loading Capacity of Defective Cable Tunnel Structures

With the popularized application of underground cable tunnels in China, various structural defects such as cracking, deforming and material deteriorating also emerge. In cable tunnels that have been poorly maintained for a long time, there is always a coexistence of several kinds of defects, and with the current methods of monitoring, it is difficult to identify the major defect affecting the load-carrying capacity and resolve it. However, the finite element method (FEM) can better solve this problem by analyzing the effect of a single defect parameter separately. In this paper, four different types of cable tunnels, namely the circular, rectangular, arched and trenched sectional tunnels, are modelled and analyzed with FEM. Defect parameters, including crack dimensions and concrete deterioration, are considered as variables, which are controlled and studied respectively. The results of the simulation indicate that the impact of crack propagation on the residual-bearing capacity of cable tunnels is much larger than that of concrete deterioration, especially the deepening of cracks. Works in this paper have the potential to be further referenced for cable-tunnel structure estimation and defect prevention.

Influence of Ventilation Duct Parameter Optimization on Pollutant Diffusion in Spiral Tunnels

The spiral tunnel could flexibly design the curvature and slope of the tunnel according to the geological structure, avoiding the adverse effect of complex terrain and topography, and had a strong advantage in engineering applications. Different from ordinary straight linear tunnels, spiral tunnels have a circular trend with obvious curvature and slope, which ensures certain differences between construction ventilation of the two types of tunnels, especially in terms of ventilation air flow field and pollutant diffusion. Relying on the actual spiral tunnel project, this paper studies the diffusion mechanism of ventilation pollutants in spiral tunnel construction. Optimization of the layout of the air duct based on numerical simulation and proposed pulsating ventilation method was performed to improve the ventilation and drainage effect of the tunnel. The time to reach the carbon monoxide concentration after blasting, and the dust concentration during the spraying process, were determined as indicators to measure the ventilation effect during the construction period. The hanging position of the air duct, the distance from the air duct outlet to the palm face, and the air speed were determined as the main factors affecting the ventilation effect. The main factors, the degree of influence and sensitivity of each influencing factor on the index, are studied, and the optimal air duct layout scheme suitable for the site is determined. The scheme can improve the ventilation effect and ventilation quality and provide effective reference for ventilation problems during the construction of other spiral tunnels. Meanwhile, more factors need to be examined to study the impact of pollutants in spiral tunnel construction, and physical models are needed to study the diffusion mechanism of pollutants in a spiral tunnel.

Off-Ramp Vehicle Mandatory Lane-Changing Duration in Small Spacing Section of Tunnel-Interchange Section Based on Survival Analysis

Due to topography, geology, and other factors, small spacing sections are common between tunnels and interchange exits. There is mandatory lane-changing behavior for vehicles that need to leave the main line and drive inside the road before leaving the tunnel. Affected by the “white hole” of a tunnel, the lane-changing behavior of off-ramp vehicles differs significantly from that of original roadbed sections. To study the mandatory lane-changing duration (MLCD) of off-ramp vehicles in small spacing sections of the tunnel to interchange in mountainous areas, their time and trajectory data were collected based on a driving simulator. According to the characteristics of the data, the survival analysis method was used to analyze the influence on the MLCD of off-ramp vehicles of the spacing section between the tunnel and interchange, vehicle types, tunnel types, ramp types, highway service level, and whether to set exit advance guide signs in the tunnel and the Cox proportional hazards model of the MLCD was established. The results showed that the spacing of the tunnel interchange, the road service level, and whether to set exit advance guide signs in the tunnel had significant effects on the MLCD of vehicles, while the vehicle, the tunnel, and the ramp types did not. When the spacing section of the tunnel interchange was less than 500 m, the off-ramp vehicle had continuous mandatory lane-changing behavior, and when the distance decreased from 400 m to 300 m, the risk rate of lane changing increased by 5.68 times. Survival function curve estimation provided the 75% quantile of MLCD of off-ramp vehicles under different conditions, which could provide a theoretical reference for setting the minimum distance between a tunnel and interchange exit.

Stability of steel pile walls and tunnels excavated by shield machines in the urban areas: A case study

Placement of infrastructure and other facilities underground brings superior opportunities for long-term improvements in terms of the environmental impact of urban areas and more efficient use of underground space. However, underground construction in urban areas is a high-risk activity and has been considered a challenging problem for geotechnical and structural designers. Therefore, the evaluation of the stability of underground structures plays a vital role in structural and construction design. This paper presents a case study on analyzing the stability of steel piles walls and tunnels excavated by shield machines in the urban area in Vietnam in terms of the change in internal forces in the structures. The research results show that the excavated stages of the basement influence on the values of internal force in the tunnel lining. In the case of study using composite lining in the tunnel, the thickness of lining concrete 35 cm, steel frame type I-W1000×883 are applied for tunnel excavated before construction of nearby basement, and 30 cm and W1000×350 steel ribs for the opposite side. This research could be applied to evaluate the effects of tunnel excavation near the existing structures in urban such as in the geological conditions in the Ha Noi and Ho Chi Minh City in the near future. However, this analysis also has the disadvantage that it does not consider the construction time as well as the construction sequence of the works during tunnel excavation. The shapes of the tunnel only are circular tunnels and the only type of steel piles in this research. Further study, total evaluation for other types of tunnels and walls of basements should be considered.

Low-Energy Fruit Dehydration Method

This article describes a low-energy fruit dehydration method. To evaluate the effectiveness of this method, an experimental fruit dehydration plant of the tunnel type was developed, on the basis of which the studies were carried out. Convection and microwaves have been used to treat the fruits during the dehydration process. The results obtained on the basis of the proposed method were compared with those obtained when using the classical dehydration method. Thus, studies have shown that dehydration of fruits by the new method allows of reducing electric energy consumption by 4.69 times.

Design and characterization of Ge/SeO2 heterojunctions as tunneling thin film transistors

Herein stacked layers of germanium and selenium oxide are employed to fabricate heterojunction devices that can perform as a multifunctional thin film transistors (TFT). The stacked layers of Ge and SeO2 are coated onto ultrasonically cleaned glass and Ag thin film substrates using thermal deposition technique under a vacuum pressure of 1.5×10−4 mbar. The stacked layers are structurally, morphologically, optically and electrically characterized. It is observed that while amorphous germanium films exhibit two energy band gaps of values of 3.56 and 0.78 eV, amorphous SeO2 show one band gap of 3.70 eV. The conduction and valence band offsets at the Ge/SeO2 interfaces are 2.24 eV and 0.68 eV, respectively. Optically, the coating of SeO2 onto Ge films enhanced the light absorbability of SeO2 by ~ 50 times (at 2.38 eV) and ~17 times (at 1.71 eV) in the visible and infrared ranges of light, respectively. Formation of Ge/SeO2 is associated with a redshift and blue shift in the values of the energy band gaps of SeO2 and Ge, respectively. In addition, the current-voltage characteristic curve analyses have shown that Ag/Ge/SeO2/Ag TFTs is of tunneling type showing an estimated peak to valley current ratios of 2.0. The TFT displayed additional functionalities presented by PMOS characteristics, microwave resonators, negative capacitance sources and multiband band stop filters. The features of the devices nominate them for use in microwave technology as band stop filters of notch frequencies of 1.10 and 1.53 GHz.

A comparative investigation between the beam spring method and the modified routine method in special‐section shield tunnels: A case study for quasi‐rectangular tunnels

AbstractThe modified routine modelling (MRM) and the beam spring modelling (BSM) are two of the classical design methods for circular shield tunnels, but a comparison between their applications in special‐section shield tunnels (SSSTs) has not yet been conducted. In this study, these two methods are investigated and compared specifically for the case of quasi‐rectangular shield tunnels (QRSTs). While the MRM gives acceptable results for axial force values, some critical bending moments in joint sections and segment sections can be overestimated or underestimated, not giving accurate values for design. It is demonstrated that the MRM cannot precisely predict the degree of bending moment transfer and convergence deformations of the studied SSST, and should only be used in preliminary design. On the other hand, deeper insights into the mechanical behaviour of the QRST lining structure can be gained through the analysis of the BSM. The staggered assembly pattern results in a bending moment transfer between rings and the relatively stiff area sustains the transferred moment from its neighbouring less stiff areas. For most of the longitudinal joints, 20% to 40% of bending moment is redistributed to its neighbouring segments. The transfer increases the non‐symmetric distribution of bending moments in the two halves of a QRST lining ring. This characteristic does not exist in a traditional circular shield tunnel but needs due attention to the types of shield tunnels with two compartments in one tube. Finally, the influences of different parameters related to the assumed pressures and soil reactions are discussed.

Yb/WO3/Yb back to back Schottky barriers designed as voltage controlled rectifiers and as microwave resonators

Herein, 𝑝 −WO3 thin films coated onto ytterbium thin film substrates are used as active layers to fabricate a back to back Schottky (BBS) barriers. The Schottky contacts and the tungsten oxide active layers are grown by the thermal evaporation technique under a vacuum pressure of 10-5 mbar. The films are structurally, morphologically, optically and electrically characterized. The physical nature of the grown 𝑝 −WO3 layers is amorphous comprising excess oxygen in its composition. Electrically, the BBS devices displayed a biasing dependent current rectification ratio confirming the tunneling type of Schottky barriers. The current conduction are dominated through tunneling barriers of height of ~0.80 eV. The barriers allow hole tunneling within energy barriers of widths of ~45 nm and of 300 nm under reverse and forward biasing conditions, respectively. In addition, the impedance spectroscopy measurements have shown the ability of wide tunability of the resistance and capacitance of the devices resulting in a microwave cutoff frequency exceeding 2.0 GHz. The resistive and capacitive features of the devices in addition to the microwave cutoff frequency spectra nominate the Yb/𝑝-WO3/Yb BBS devices for use as microwave resonators suitable for 4G/5G technologies.

Analysis of the Reformulated Source to Drain Tunneling Probability for Improving the Accuracy of a Multisubband Ensemble Monte Carlo Simulator.

As an attempt to improve the description of the tunneling current that arises in ultrascaled nanoelectronic devices when charge carriers succeed in traversing the potential barrier between source and drain, an alternative and more accurate non-local formulation of the tunneling probability was suggested. This improvement of the probability computation might result of particular interest in the context of Monte Carlo simulations where the utilization of the conventional Wentzel-Kramers-Brillouin (WKB) approximation tends to overestimate the number of particles experiencing this type of direct tunneling. However, in light of the reformulated expression for the tunneling probability, it becomes of paramount importance to assess the type of potentials for which it behaves adequately. We demonstrate that, for ensuring boundedness, the top of the potential barrier cannot feature a plateau, but rather has to behave quadratically as one approaches its maximum. Moreover, we show that monotonicity of the reformulated tunneling probability is not guaranteed by boundedness and requires an additional constraint regarding the derivative of the prefactor that modifies the traditional WKB tunneling probability.

ANALISA VARIASI TEKANAN, TEMPERATURE, UKURAN RUNNER TERHADAP FILLING TIME OPTIMAL PADA INJEKSI MOLDING

AbstractPlastic based packaging systems for food box lid products receive special attention from manufacturers and the most common process is injection molding. This study aims to analyze the effect of variations in pressure, temperature, and runner size on filling time in the injection molding process for food box products using Autodesk Inventor 2015 software in order to obtain the optimal filling time. Experiments in the form of simulations were carried out by entering data on variations in pressure, temperature, and runner size. The results of this study obtained the optimal filling time at the melting temperature setting of 220℃, injection pressure of 90 Mpa, mold temperature of 40℃, and runner diameter of 6 mm. The optimal type of gate tunnel and runner circle type has a filling time analysis result of 0.34 seconds. Defects that occur during the injection molding simulation process are weld lines, air traps and short-shots. Based on these problems, a mold unit was designed with a two plate mold system type. Keywords: Plastic, Injection Molding, Experiment, Lid Food Box, Inventor, Mold.

Технологии снижения риска возникновения чрезвычайных ситуаций на автодорожных развязках тоннельного типа

PURPOSE. Tunnel type road junctions considerably reduce traffic load in metropolitan areas, but they are also high-risk facilities. Any emergency in a confined space can result in loss of life and significant property damage. This is confirmed by the fact that over the past decade alone, more than 100 people have died in the tunnel fires. Thus, the development of emergency situations risk reduction technology is a crucial task. METHODS. A review of regulatory documents that establish requirements for the integrated safety of high-risk facilities, including tunnels, has been carried out. The ways of improving safety of tunnel type road junctions have been analyzed. The findings of our own research as well as the international and national experience of integrated safety provision for high-risk facilities have been discussed. FINDINGS. Based on the analysis of literature references and the results of our own experimental studies, the prospects for scientific research on creating integrated automated systems for monitoring safety and life support of tunnel type road junctions have been defined. It is determined that in order to improve the safety of tunnels it is necessary to use the technology of structured systems for monitoring and controlling engineering systems of buildings and structures developed with the participation of the authors (SMIS). RESEARCH APPLICATION FIELD. The obtained results provide the basis for further technologies development for improving the integrated safety of high-risk facilities by using automated systems integrated with each other for monitoring safety and life support of buildings and structures. CONCLUSIONS. The proposed technology for creating SMIS at tunnel type road junctions makes it possible to significantly increase their security. At the same time, when creating SMIS for tunnels it is appropriate to comply with the following requirements: to develop SMIS in the form of a modular structure, automated control over the operation of safety and life support systems should be provided, to develop SMIS as of an “open system” to which it will be possible to extra connect new safety and life support systems.

Study on the temperatures of railway tunnel side ditches in high-latitude cold regions based on the effects of wind

Tunnel side ditches in the high-latitude cold regions of China experience severe freezing-induced damage. In this paper, a three-dimensional transient temperature calculation model for tunnel in cold area is proposed, and the reliability of the temperature calculation model is verified by the field test results. The characteristics of tunnel temperature distribution under the influence of many factors, especially tunnel section and tunnel length, which are ignored in the existing research, are studied. The influence of tunnel design parameters on temperature field under different railway tunnel types (single-track and double-track tunnel) was also studied. The results show that the length with a temperature below 0 °C of single-track tunnel increases with the increase of tunnel length, while that of double-track tunnel decreases. No matter what type of tunnel, increasing the train frequency and train speed can significantly increase the freezing range of the tunnel. However, the influence of piston wind on temperature distribution in single-track tunnel and double-track tunnel is very different. For single-track tunnel, the growth rate of the length with a temperature below 0 °C decreases with the increase of train speed; However, for double-track tunnel, the growth rate of the length with a temperature below 0 °C increases with train speed. The frost damage of double-track tunnel in cold area is more serious than that of single-track tunnel. Under the same conditions, the antifreezing length of double-track tunnel is much longer than that of single-track tunnel. Based on the calculation results, a prediction model for the freezing length of cold-region tunnel side ditches was proposed, thereby providing a reference for the prevention and control of freezing-induced damage in the side ditches of cold-region tunnels.

Modelling a virtual wind tunnel for vehicle aerodynamic measurements

The automotive makes of our days are challenged to fulfil more and more criteria to remain competitive and financially performant, considering the legislation that must be respected to be able to commercialise each model. One highly important set of rules focus on emissions and strict limits are implemented. To develop compliant products, each make must focus on aerodynamic performance so to reduce the drag of air, thus the required force to overcome for movement at high speeds. While homologation is currently done exclusively as a physical test, to be able to reduce the aerodynamic coefficient, strong virtual tools are used. These measurements performed with computation fluid dynamic software are translated into a virtual wind tunnel that must be able to give relevant and coherent results in respect to final physical validations. The paper will indicate the main types of wind tunnels, parameters to consider, error source and how results can be used. While the computational power is growing each moment, the industry is continuously adapting to obtain the most performant and appealing designs with minimal resources, this being the key of reducing the CO2 footprint of passenger vehicles transport segment.

Analysis of Important Factors Having an Impact on Safety in Road Tunnels – Research Findings

Aim: This article presents relevant safety issues in road tunnels based on the results of a survey and evacuation experiments conducted on real scale in two existing road tunnels in Poland. Project and methods: An analysis of the relevant factors influencing the level of safety in road tunnels was carried out based on the results of experi - mental studies in two road tunnels in which the course of evacuation under fire conditions was observed. As part of the study, several evacuation trials were carried out at equal smoke levels, examining a different parameter each time: pre-movement time, speed of movement, the effect of smoke on the speed of movement, the effect of tunnel infrastructure on evacuation, among others. A survey carried out among 504 respondents, in turn, attempted to assess the awareness of hazards and safety procedures in road tunnels. The survey has four parts and questions covered the following issues: knowl - edge of tunnel infrastructure, behaviour in case of congestion, choice of evacuation route, behaviour during the evacuation, personal belongings during the evacuation, self-assessment of tunnel safety knowledge and the role of experience. An analysis was also carried out of the information available in Poland on safety guidelines for road tunnels, which can help tunnel users to improve their knowledge on tunnel safety. Results: The survey results indicate an insufficient level of knowledge regarding safety in road tunnels – only 16% of respondents answered more than 50% of the questions correctly. Ignorance of road tunnel infrastructure itself and the safety rules for the tunnel was also diagnosed. An analysis of the information available to the road users demonstrates that this information is difficult to access and that there is a lack of uniform guidelines to educate the public on the topic raised in the article. A significant impact of evacuation exercises carried out on an accurate scale was emphasised, providing valuable data on the evacuation process and increasing the level of safety in the engineering facilities analysed by raising the awareness of the partici - pants in the experiment. Conclusions: The research findings presented in this article allow for better understanding of the behaviour of the participants of accidents and fires in road tunnels. In addition, the need to raise the awareness of the road users on the dangerous situations that may occur in a tunnel and the appropriate response to them has been demonstrated. Keywords: safety, fire, smoke, evacuation, road tunnel Type of article: original science article

A New Perspective for Ni-Doping into Tunnel Type Na0.44mno2 Nanorods: Enhanced T/P2 Hybrid Cathode Material for Sodium-Ion Battery

A New Perspective for Ni-Doping into Tunnel Type Na0.44mno2 Nanorods: Enhanced T/P2 Hybrid Cathode Material for Sodium-Ion Battery

Synthesis of titanates for photomineralization of industrial wastewater and organic pollutants

The optical parameters of tunnel type titanates NaTO, PdTO and Ag/PdTO were studied and they were used as photocatalysts for the photomineralization of various organic dye pollutants and industrial wastewater (IWW) under visible light irradiation.