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Highlights • Full-scale experiments were carried out in a real road tunnel. • The airflow velocities were measured for one cross-sectional profile. • The natural caused airflow and different fans operation modes were examined. • Theoretical considerations on natural caused airflow in the tunnel was presented. Abstract This article presents the results of full-scale in situ measurements of airflow, conducted in a real-world road tunnel. The tunnel is located in Gdańsk city under one of the limbs of the Wisła river. The total length of the tunnel is 1378 m and the middle section of the tunnel is located at the deepest level. The inclination of the road is 3% and 4% for both directions from the deepest point. The tests covered measurements of airflow at 56 separate measuring points. The natural draught was determined, in addition to airflow rates for varying configurations of jet fan operation. The results were compared to those which were taken from automatic tolls mounted in the tunnel. The article also contains a theoretical discussion concerning a method for determining the natural draught in a tunnel. [ABSTRACT FROM AUTHOR]

An overview of ways of jet fan modeling with the use of Ansys Fluent methods is presented. The theoretical models were built and validated basing on the experimental measurements made by Giesen et al. (2011). The results obtained with the all models were compared with this experimental data and next the detailed discussion was provided. A special attention was paid to the turbulence modeling, the range and the shape of the jet produced by the fan. Ansys Fluent supports three suitable approaches allowing for accurate mapping of the axial fan operation, which differ in the degree of simplification of the reality. The first approach involves modeling a fan as a volume source of momentum. All three momentum components can be set, so the fan axis can be freely oriented in the space. The second approach involves modeling a fan with known characteristic. A fan is here a 3D object, but the fan rotor is a plane surface of zero thickness. The model is more accurate, but requires a set of parameters, which should be determined by the measurements. In the third approach a fan is also modeled as a 3D object, in this case the rotor has the real spatial dimensions. This model is capable to calculate all fan features by itself, but requires more computational resources. Apart from the above the fourth fan model as a velocity inlet is willingly used. The selection of the model is dependent on data available and required minuteness of the fan representation and operation. [ABSTRACT FROM AUTHOR]

This work presents experimental and numerical research on the solar updraft at a tall building façade, which is 55 m high. The measurements are carried out in windless and cloudless weather, so the warmed by the solar irradiation façade is almost the only factor causing the buoyancy-driven airflow. A set of anemometers are used to record the vertical component of the air velocity. The mean value of the airflow velocity reached up to 2 m/s. However, the instantaneous value varied up to 4 m/s. A numerical model for the solar updraft is built using an ANSYS Fluent, and the temperature boundary condition at the façade is set based on a real IR image taken during the measurements. The numerical results are consistent with the experimental data and the theoretical considerations – at the upper façade edge, the total thickness of the buoyant plume is determined to be about 5 m, and the average airflow velocity is around 0.7 m/s. The strongly turbulent nature of the solar updraft is also confirmed. • The airflow velocity for the solar updraft at a tall building façade was measured. • A numerical model of the solar updraft at a tall building façade was built. • A strong solar updraft was revealed, the average airflow velocity was over 2.5 m/s. [ABSTRACT FROM AUTHOR]

Smoke management in the atrium with natural smoke venting is influenced by many parameters. The analysis presented considered the impact of atrium height, atrium shape and layout of air inlets, wind direction, wind speed and location of the fire outbreak. Experimental research is here very awkward due to the costs, thus the numerical analysis is a convenient way to examine such a large parameters domain. So wide range of research was feasible thanks to the use of Taguchi method of experiment design. The flow volume through the exhaust vents and the soot mass fraction at the ground floor were chosen as criteria to evaluate the efficiency of the smoke removal system As a result, the relative importance of examined parameters were obtained, and above all the interactions between parameters were revealed. This allows to formulate some hints for designers to make the smoke removal systems robust on the wind influence and other unpredictable factors. [ABSTRACT FROM AUTHOR]

The main aim of the research performed was to check the operation of a ventilation system in a conventionally operated road tunnel in Southern Poland. The length of the examined tunnel is 678 m and it has a gradient of 4%. It includes longitudinal ventilation. The measurements of normal and reversed velocity of air flows (which were forced by the fans) were conducted at two cross-sectional profiles inside the tunnel. A set of fourteen thermal anemometers was applied there. In addition, at the intake and exit portals the wind direction, wind velocity and temperature were recorded during the tests. The fans worked according to the emergency operation pattern. The results were compared to estimated critical velocity and the correct functioning of the ventilation system was confirmed. The results showed a significant influence of the naturally caused airflows. Numerical simulations were performed to determine the air velocity resulting from this effect. CFD Ansys Fluent was used to solve the simplified model of the tunnel. The results confirmed that the combination of the stack effect and wind influence is crucial. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanism of the piston effect is analyzed. • An analytical formula for airflow velocity due to the piston effect is proposed. • An algorithm for assessing the external wind impact on tunnel airflow is proposed. • The results are compared with the bulk data recorded by tunnel sensors. A novel analytical formula is introduced for calculation the average longitudinal airflow velocity in tunnels as a result of the piston effect. Existing correlations were analyzed and reworked to better represent the piston effect of vehicles travelling in bulk, which allows relating the airflow velocity to not only average vehicle velocity, but also the traffic intensity and the traffic structure. The approach was validated using the recorded bulk data for an urban road tunnel located in Gdańsk (Poland). Air velocity, weather conditions, wind parameters at tunnel portals, traffic intensity and structure as well as average traffic speed by lane were recorded at 1 s intervals, and analyzed in form of 10 s and 5 min averages. Since ambient conditions may affect the flows inside the tunnel, their impact on flow measurements was studied with a numerical model of the tunnel portals. Despite its simplicity, the proposed model accurately predicted the air velocity due to vehicle movement. The significance of this approach is related to the ease of achieving the initial data, which allows for easy implementation in tunnel ventilation design, risk assessment methods, determination of initial conditions for fire related CFD analyses, continuous tunnel management or estimation of the potential of energy recuperation from airflow within the tunnel. The mean absolute error (MAE) of calculated air velocity to measurements was 0.28–0.38 m/s, with mean average percentage error (MAPE) of 7.8–10.9 %. The determination coefficient for the relation with the measured data was significantly over 0.9. [ABSTRACT FROM AUTHOR]

Abstract: The research was focused on the analysis of writing inks using the laser induced breakdown spectroscopy (LIBS) technique. 34 samples of blue, 30 of black, and 21 of red writing inks were analyzed under optimized conditions to determine the variation of chemical composition of inks between different colours, brands and types. Nine elements (Ba, Cr, Cu, Fe, Li, Mo, Mn, Ni and W) were taken into account during comparative analysis of inks. Because of the strong effect of the paper spectrum, elements often found in inks (Ca, Al, Mg, Na, Ti, and Si) were eliminated from LIBS analysis of inks. It was determined that the LIBS method is capable of revealing qualitative elemental differences between ink samples. The discrimination power of this method was found to be 83, 82 and 61% for blue, black and red inks, respectively. Inks produced by the same producer were able to be differentiated in some cases. The results showed the potential of LIBS for forensic purposes as an effective and robust technique, requiring a small amount of sample and giving analytical information in a very short time. [Copyright &y& Elsevier]

Questioned document examination in a wide variety of criminal and civil cases often focuses on the identification and comparison of stamp inks. Increasingly frequent counterfeiting of documents, especially those that have been stamped, has led to a growing need for instrumental methods that will allow an in-depth examination of stamp inks on a document. Therefore, the usefulness of two capillary electrophoresis techniques: micellar electrophoretic capillary chromatography with UV/Vis diode array detection (MECC-DAD) and capillary zone electrophoresis with electrospray mass spectrometric detection (CZE-ESI/MS) was verified for this purpose. Violet, red, blue and green stamp inks on paper surfaces were investigated. Electropherograms and mass spectra of inks purchased from 10 different producers were obtained in accordance with optimized and validated analytical procedures. It was shown that effective differentiation of individual inks was possible in terms of migration time and UV/ Vis spectra provided that there was more than one characteristic peak. However, the most problematic inks with only one very similar (or identical) dye component - violet and blue ones - were additionally differentiated by CZE-MS. The obtained results showed that the proposed procedures can be useful for the objective analysis of questioned documents involving stamp inks. Consequently, the developed methods can be applied in the forensic field, including in the investigation of the authenticity of documents. [ABSTRACT FROM AUTHOR]

• Fire scenarios for a congested urban tunnel are examined. • An algorithm for assessing the fire safety level in a urban tunnel is proposed. • Individual histories of evacuees are visualized. • Some propositions of increasing the safety level in urban tunnels are provided. A fire outbreak in a urban tunnel with congested traffic may pose a great danger to all tunnel users. The main threat to human life in an urban tunnel fire is thick toxic smoke quickly filling large parts of the tunnel. It hinders evacuation and may even lead to lethal intoxication. Due to the potentially rapid development of the fire, people trapped will need to evacuate on their own. Thus, tunnel safety systems must support their self-rescue efforts. In this paper, several scenarios of fire accidents in a real urban tunnel are numerically investigated. The scenarios differed in road traffic state, fire power and fire detection time. To make them realistic the entire sequence of events during a tunnel fire was numerically modeled. First, the formation of congestion is examined using VISSIM software, then fire development is simulated by Fire Dynamic Simulator and finally, the evacuation process is modeled by PATHFINDER software. All data needed to build these numerical models correspond to real conditions of the selected urban tunnel under the Martwa Wisła river in Gdansk (Poland). The outcomes of the work suggest the number of threatened people may be very large even under common circumstances. In the worst case over a half of people trapped inside may come into contact, at least temporarily, with factors threatening health or live. [ABSTRACT FROM AUTHOR]

A fire outbreak in a road tunnel is the most dangerous threat to the people who are trapped inside. The main danger is the generation of large amounts of toxic smoke. Tunnel fires develop in an unpredictable way, but the conditions get worse very quickly. Therefore the self-evacuation involving suitable decisions and proficient actions is of crucial importance. The work presents a number of scenarios of the tunnel fires and the following evacuation. Different tunnel fire detection delays, types of ventilation system, traffic conditions, fire locations and fire powers were taken into account. The research was conducted by the combined numerical simulation: VISSIM software was used to simulate the traffic and the formation of congestion, FDS was used to reproduce the fire development and PATHFINDER was used to simulate the evacuation and to estimate injures. To embrace the great number of factors influencing the described issue the Taguchi method of experiment design was applied. It allowed also for determining the relative influence of these factors on the evacuation process. • Factors influencing the safety level in a road tunnel were studied. • Combined simulations using VISSIM, FDS and PATHFINDER were used. • Taguchi method of experiment design was applied. • Individual histories of evacuating people were analyzed. [ABSTRACT FROM AUTHOR]

• Factors influencing the accuracy of numerical models of airflow in a tunnel were discussed. • A short discussion of the selection of suitable turbulence model was presented. • Calculated profiles of air velocity were compared to the measurements. • Compliance at the level of the detailed air velocity distribution was obtained. • Some tips for building reliable numerical model of tunnels are listed. The paper presents the results of the numerical modeling of the air velocity distribution in a road tunnel. The results were validated by full-scale in situ measurements of air velocity in a normally operated real tunnel. The preparation of the numerical models was preceded by a detailed study on the selected features influencing the structure of modeled flow. Eventually, the results of numerical simulations were compared with those of the measurements. The overall distributions of air velocity were almost the same as the experimental values; slightly larger deviations were observed only at a few points close to the tunnel walls. The variation of the calculated velocity did not exceed 9%, which proved the reliability of the numerical models. The conclusions also include certain recommendations which would be helpful for those who facing the issue of numerical modeling of airflows in tunnels. [ABSTRACT FROM AUTHOR]

• The full-scale measurements of airflow in a road tunnel are presented. • A CFD model of the spatio-temporal airflow structure is introduced. • A theoretical model of airflow dynamics is introduced. • Longitudinal and semi-transverse operation modes are compared. This paper presents full-scale experimental, numerical, and theoretical research on the spatial and temporal structure of airflow for different modes of ventilation system operation in a road tunnel. The tunnel under investigation is equipped with a semi-transverse ventilation system. There are 19 pairs of axial jet fans in each tunnel tube and 164 air supply vents on both sides of a tube located just above the road surface. A set of seven stand poles with mounted vane anemometers were arranged along the tunnel tube axis. Different configurations of axial jet fans and air supply vents were employed, and changes in airflow velocity were recorded. Since the main objective of the study is to achieve a deeper understanding of the examined phenomena, a numerical model of the flows in the tunnel was built, and the acquired data was used to validate it. Some theoretical considerations are provided and also validated. All of this together reveals a very uneven distribution of longitudinal air velocity along the tunnel axis. Then, time constants when switching the fans on and off are determined. It is shown that the time needed to achieve a stable flow after the fans are turned on is in the order of five minutes, and the decay time after the fans are turned off is much longer; it takes about 15 min to calm down the flow. Next, it is determined that the transverse air supply significantly changes the airflow structure: the average longitudinal air velocity at the inlet portal was up to 25% lower than without it, while values at the outlet portal were similar. Finally, it is indicated that axial fans that operate in the suction mode are similarly efficient to those in the pumping mode. [ABSTRACT FROM AUTHOR]

Background Recently, novel protocol utilizing Continuous Mononuclear Cell Collection (cMNC) have been introduced for leukapheresis. We compared the efficacy of cMNC with an older protocol – mononuclear cell collection (MNC) for CD34+ cell collection in unrelated donors with negative stem cell collection predictors. Material and methods Retrospective data from a series of 258 consecutive unrelated hematopoietic stem cell donors was included in this single-center study (80 donors collected with cMNC and 178 with MNC). The donors with poor predictors for collection such as low number of circulating CD34+ cells and/or weight disproportion were assigned to the cMNC arm. Results The cMNC protocol yielded a higher number of CD34 + cells per donor body weight (7.63 × 10 6 /kg vs 6.82 × 10 6 /kg, p = 0.027). One apheresis was sufficient for collection of target cell number in 89% individuals from both groups despite negative predictors in the cMNC group. In donors with CD34 + cell count <100/μL and a body weight disproportion between donor and recipient one apheresis was sufficient in 83% of donors in cMNC group and in 58% in MNC group (p = 0.0345) with collection efficiency CE2% values of 61% for cMNC and 62% for MNC (p = 0.77). Conclusion cMNC protocol is more efficient in donors with low pre-apheresis CD34+ cell count and weight disproportion between donor and recipient. This suggests that the use of cMNC in unrelated donors could possibly further improve the results of HSC collections. [ABSTRACT FROM AUTHOR]

Hydrogen-blended natural gas has widely used in energy fuel systems in industrial and domestic applications. During storage, transportation and usage of the fuel, temperature characteristics make a key contribution to energy leak gas fire accidents. In this manuscript experimentally, the buoyant turbulent diffusion axial temperature profile of a hydrogenated methane jet fire is experimentally investigated under free fire and wall fire. Different hydrogen addition ratios, nozzle diameters, and fire heat release rates were considered in the experimental conditions. Temperature profiles and virtual origins were recorded and analyzed. It is found that the wall fire temperature is somewhat higher than that in the free fire at a fixed height. And the vertical temperature of the jet fire increases with the increase of the hydrogen addition ratio, while the flame height decreases. With the addition of hydrogen, the virtual origin is increased, and virtual origin of wall fire is clearly larger than that of the free fire. Due to the restriction of air entrainment from the sidewall and the hydrogen addition, the physical mechanism of restricted air entrainment was analyzed. In addition, a non-dimensional model of the virtual origin was proposed and analyzed for different conditions. Finally, the normalized vertical temperature profile in the continuous flame region, intermittent flame region and buoyant plume region based on the virtual origin and mirror-approach are still well characterized for air entrainment under all conditions. The results of this paper may demonstrate the potential for the risk assessment of hydrogen-blended natural gas fire. [ABSTRACT FROM AUTHOR]

The identification of forged and genuine historical banknotes is an important problem for private collectors and researchers responsible for the care of numismatic collections. This paper presents a research approach for detecting material differences in historical banknotes through the use of microfading spectrometry along with other techniques such as hyperspectral image analysis, Fourier-transform infrared spectroscopy, and X-ray fluorescence spectrometry. Microfading spectrometry results showed higher sensitivity to light irradiation for an overprint ink used on a suspicious banknote relative to its counterparts. In addition, the spectrocolorimetric changes experienced by the paper substrates during microfade testing also provided a way for discriminating between two groups of banknotes. These variations have been confirmed after analyzing the spectral and physico-chemical data obtained using the abovementioned complementary techniques. [ABSTRACT FROM AUTHOR]

There are many reports on factors predicting the outcome of PBSC (peripheral blood stem cell) mobilization, such as the donor's gender, age, weight, white blood cell count, platelets pre apheresis, LDH and iron status. Although there are reports of seasonal variation in the physiology of the human immune system and hematopoiesis there are no data that such differences play a role in the response to G-CSF in healthy hematopoietic stem cell donors. The response to G-CSF could also impact the collection results during different seasons. To assess the possible impact of seasonal variation we performed a retrospective, single-center analysis of mobilization and harvest of PBSC in 330 healthy unrelated donors. We found no significant differences in the number of CD34+ cells in peripheral blood after G-CSF mobilization and in collection results when all donors were analyzed. In the subgroup of male donors the number of CD34+ stem cells after G-CSF mobilization was higher than average in summer and autumn (p = 0.036), however, it did not translate into clinically relevant differences in stem cell harvest. We conclude that although there is possible seasonal variation in the response to G-CSF in male donors there is no impact on PBSC harvest in healthy unrelated donors. [ABSTRACT FROM AUTHOR]