Natural Wind Research Articles

Turbulence characterization of instantaneous airflow above passengers with different air distribution systems in a commercial airliner cabin

The environment inside airliner cabins has attracted increasing attention. Instantaneous airflow, as one of the fundamental parameters of airflow field, affects aspects of the airliner cabin environment such as occupant comfort and airborne disease transmission. This study evaluated the characteristics of instantaneous airflow in airliner cabins with different ventilation systems (mixing ventilation and displacement ventilation) and focused on the region above passengers' heads, where complex turbulence characteristics are found. This investigation used ultrasonic anemometers for measurements at ten selected points above passengers' heads. The energy ratio on the low-frequency scale with mixing ventilation was greater than that with displacement ventilation. The instantaneous airflow with mixing ventilation was close to that of natural wind, while the instantaneous airflow with displacement ventilation was close to that of mechanical wind. Compared with mixing ventilation, displacement ventilation produced a smaller vortex length and a shorter residence time. Moreover, there was no long-term vortex in the flow field under displacement ventilation, and therefore, pollutants would be discharged more quickly from the cabin. In addition, this paper distinguishes the spatial and temporal turbulence scales of mixing and displacement ventilation, thus providing a reference for the selection of grid size and time steps in computational fluid dynamics simulations.

A new meteorological pressure index to support a sustainable nuclear energy programme

Today, the evaluation of a site for innovative nuclear installations represents a fundamental step in supporting the implementation of a sustainable nuclear power program. One major concern is the potential for radioactive releases and their effects on the biosphere, particularly on human health. To address this issue, a new Meteorological Pressure Index (MPI) has been developed to identify sites with resilience capacity in terms of transport phenomena correlated to natural wind actions on a regional scale. The MPI utilizes a fuzzy approach that combines data on 3D wind speed, direction, and frequency, providing maps that are useful in the site selection process. The application of MPI in the Sicily region of Italy has allowed to identify bordering areas that that are more affected by efficient air mass transport mechanisms. Consistency analyses have been conducted among MPI maps, observed wind distributions using wind rose charts, and stagnation S and recirculation R factors. The results confirm the MPI's ability to aggregate meteorological data on a regional level, making it a suitable tool when compared to disaggregated data that may not always provide a comprehensive viewpoint.

Experimental Performance of a Novel Dual−Stage Counter−Rotating Small Wind Turbine and Forming a Validatable CFD Computational Model

This paper publishes the experimental performance results of a novel small dual−stage wind turbine at different speeds under wind tunnel testing. The results confirm its superiority at low wind speeds <7 m/s, which is consistent with natural wind conditions in most countries around the world. At lower wind speeds, the efficiency of the small, dual−stage wind turbine is higher than that of a conventional single−stage turbine. At wind speeds of <6 m/s, the novel dual−stage wind turbine always produces approximately 2.5 times more power than a single−stage wind turbine; the power coefficient is greater than 0.4. Thanks to this feature, the novel small, dual−stage wind turbine is effective in practical applications. For windy areas in Vietnam, the power generated over the same amount of time by the novel dual−stage wind turbine can be more than double that of a single−stage turbine. Next, a standard CFD model is established and validated with the above experimental measurements. This method ensures the objectivity and authenticity of the computational model. This standard CFD model is applicable to a horizontal double−stage wind turbine with any configuration and blade profile. The URANS simulation method, which uses sliding meshes and the k−omega SST turbulence model, was implemented with rotational domains of the minimum thicknesses of rotational domains (in this paper, 0.09Rfront and 0.06Rrear, accordingly). This method predicts higher mechanical work for the turbine than the actual value by an interval of <10% in the same speed range as in the experiment. This is an acceptable deviation.

Study on Temperature Distribution along the Ultra-Long Underwater Tunnel: Based on the Long-Term Measured Results of the Shanghai Yangtze River Tunnel

Tunnels play a vital role in enhancing traffic flow and supporting public transportation systems. However, the discharge of polluted air and waste heat from vehicles passing through tunnels significantly raises the temperature inside, presenting challenges in terms of occupant comfort, tunnel safety, and infrastructure integrity. Therefore, ensuring proper temperature control is essential for their efficient operation. This study aims to investigate the phenomenon of temperature rise in ultra-long tunnels during normal operations, as limited research has been conducted in this area. The Shanghai Yangtze River Tunnel serves as a case study, utilizing temperature and air velocity data collected throughout the year (2021) from the management company. The analysis reveals that the temperature distribution near the tunnel exit is influenced by outdoor temperature fluctuations and traffic volume. The highest temperatures occur on 25 August (39.74 °C) during peak traffic hours. On-site measurements of tunnel temperature, humidity, and air velocity during winter and summer seasons yield the following results. During winter, the air temperature and wall temperature inside the tunnel experience significant increases along its length. The air temperature rises by approximately 11 °C from the entrance to the exit, while the wall temperature increases by about 15 °C. In contrast, during summer, the air temperature only rises by 2.7 °C, and the wall temperature increases by around 3 °C. Consequently, the humidity decreases along the tunnel, and this decrease is correlated with the magnitude of temperature increase. Furthermore, measurements of air velocity indicate that natural and traffic-induced winds contribute to the overall airflow inside the tunnel. A temperature data logger installed in the tunnel recorded temperature changes during the period of pandemic lockdown and subsequent recovery, spanning the spring and summer seasons. During the lockdown period, there was a relatively small increase in temperature along the tunnel, suggesting that vehicle heat dissipation is the primary factor contributing to temperature rise inside. Additionally, a method is proposed to predict the cross-sectional temperature of the tunnel using measured air velocities.

Passive heat recovery wind tower: Assessing the overheating risk in summertime and ventilation heat loss reduction in wintertime

Wind towers are low-energy ventilation devices which can provide cooling and reduce buildings’ energy use. However, during unfavourable climate conditions, wind tower operation could cause thermal discomfort and ventilation heat loss. There also has been very limited research into the overheating risk caused by wind tower ventilation. Therefore, this study explores the feasibility of the year-round operation of wind towers with solid tube heat recovery (THR) through computational fluid dynamics (CFD). The results show that within the mild-cold months, the natural ventilation wind tower with THR raised the room temperature by an average of 3.1 °C, based on the set conditions. This extended the working period of the wind tower throughout the year, especially during mild-cold months. During summertime, the highest indoor temperature observed in the space ventilated by the wind tower with THR was 24.35 °C, which meets the static overheating criteria. The wind tower with THR reduced the ventilation heat loss by up to 8.1% in wintertime. It should be acknowledged that the wind tower with THR cannot provide satisfactory thermal comfort in cold months with outdoor temperatures below 9.41 °C, and more research should be conducted to improve the heat recovery efficiency.

Utilization of Exhaust Fan from Air Conditioner for Horizontal Axis Wind Turbine with Differences in the Number of Blades

Energy needs are increasing every year in line with the increase in population, economic growth, and high energy consumption. Indonesia's fossil energy reserves continue to decline; therefore, it is necessary to increase the non-fossil energy used. Indonesia, which has an abundant supply of renewable energy sources, is a major force in this clean energy revolution. As a renewable energy source, wind energy is a good form of energy that can be developed using wind turbines. The wind source to drive the wind turbine can come from natural wind sources or exhaust wind from equipment. In addition to utilizing natural wind energy, there is also artificial wind, which is the result of waste energy from exhaust fans, as an alternative energy source option for wind power plants. In this study, the idea emerged to conduct an experimental analysis of AC exhaust fans as a wind source for horizontal wind turbines to understand the concept of wind-based DC power generation and optimize low wind speeds in horizontal axis wind turbines with a different number of blades. The numbers were 2, 3, and 5, so the effect of the resulting voltage change could be known. The final result of testing on a horizontal turbine with 5 blades was that the wind speed was 3.63 m/s, the blade rotation was 1170.8 rpm, and the turbine was able to generate a voltage of 23.50 V.

Impacts of natural and anthropogenic factors on soil erosion

Soil erosion is a serious issue that is caused by both natural and anthropogenic factors. Natural processes, including water and wind erosion, as well as higher temperatures, have been identified as leading causes of soil erosion. Additionally, anthropogenic factors, such as urbanization, road construction, agriculture, industry, mining, and others significantly contribute to this problem. These factors have resulted in the loss of biological productivity of the land and have inflicted damage on the entire ecosystem. Since 2000, soil erosion and desertification have become even more severe, exacerbating the problem. The soil of Mongolia, characterized by an arid and semi-arid climate with low precipitation and high temperature fluctuations, is highly susceptible to erosion with approximately 55% of it being classified as high or very easy to erode. This review provides a comprehensive overview of the natural processes and anthropogenic factors that contribute to soil erosion, as well as the current status of soil in various regions of Mongolia.

Roadside Retractable Wind Turbines

Abstract: The utilization of wind energy as a sustainable and clean energy source is growing rapidly, but its effectiveness is limited due to the variable nature of natural wind. However, highways offer a unique opportunity to generate significant wind energy from the high volume of vehicle traffic. In order to determine the average velocity of wind created by passing vehicles, extensive research on wind patterns is required. Wind turbines will be strategically placed on the medians of highways, with careful consideration given to fluid flow from both sides of the road. By capturing wind energy through the installation of wind turbines onto existing streetlights, an endless source of electricity for lamps and other devices can be supplied. The ultimate goal of this project is to create a sustainable and efficient wind turbine that can harness wind energy from moving cars on highways.

Shell-side heat transfer characteristics of floating liquefied natural gas spiral wound heat exchanger under sloshing conditions

To study the influence of offshore sloshing motion on the performance of a spiral wound heat exchanger (SWHE) installed on a floating liquefied natural gas (FLNG) platform and to explore potential methods to improve heat transfer efficiency, a sloshing experimental platform was established. This platform facilitated the experimental study of the boiling heat transfer process of a subcooled falling film on the outer surface of the heat exchanger tube. A quantitative analysis of the change in the heat transfer coefficient with respect to the amplitude and period of the rolling and swaying motion was performed. The experimental results indicated that both rolling and swaying changed the liquid film morphology, leading to a decrease in the heat transfer coefficient of the heat exchanger tube. The fluctuation in the heat transfer coefficient became more drastic with an increase in amplitude, but the effect of the swaying motion was less than that of the rolling motion. When the rolling angle was 12° and the Re number was 569, the average heat transfer coefficient of the round tube decreased by 55% compared with that at the static condition. Furthermore, the research encompassed the design, processing, and rigorous testing of elliptical and egg-shaped tubes to improve their heat transfer performance, and the results were compared with those of round tubes. Under the same rolling or swaying conditions, the heat transfer coefficients of the egg-shaped and elliptical tubes were 5.1–21.5% higher than that of the round tubes. The results of this study can be used as a reference for the operational and structural design of SWHEs under sloshing conditions.

Hybrid physical and data driven modeling for dynamic operation characteristic simulation of wind turbine

Accurate simulation of wind turbines is the key to achieve efficient control of wind turbines and optimal scheduling of wind power systems. Most of the existing methods are physical simulation models, which have heavy computational burden, especially for large-scale wind turbines, and the simulation accuracy is poor under complex dynamic operating conditions. In response, this paper proposes a hybrid physical and data driven model for dynamic operation characteristic simulation of wind turbines. Firstly, a database of dynamic characteristics of wind turbine operation under various wind conditions is constructed, and then the sequence learning (Seq2Seq) model is used to mine the time series characteristics of wind turbine operation parameters. Combining with long short-term memory (LSTM) network, the mapping relationship between various operating parameter time series to establish. On this basis, an attention mechanism is added to the model to learn the dynamic response characteristics of rotor inertia to natural wind process. Through numerical example analysis, the method proposed in this paper can accurately excavate and learn the time sequence dynamic characteristics of wind turbine operating conditions and parameters under various wind conditions, thereby improving the simulation accuracy and calculation efficiency of wind turbine output power and load dynamic characteristics. Taking the actual wind turbine operation data as an example, the simulation accuracy of wind turbine output power reaches 99.8%. Compared with traditional methods, and the simulation accuracy of tower root load reaches 88.5%.

GEL EXTRACTION OF EARTHWORMS (Lumbricus rubellus) TO THE NUMBER OF FIBROBAL CELLS IN MALE WISTAR RATS (Rattus norvegiccus) GINGIVAL WOUND HEALING

Introduction: Gingiva is one of the oral mucosa that is most susceptible to injury, one of the factors is surgical procedures such as curettage which will be followed by a natural wound healing process. When a wound occurs, the cells that act as the building blocks of ground substance and the formation of collagen fibers in closing the wound are fibroblast cells. Many people think of earthworms (Lumbricus rubellus) only as animal feed or fish feed, but earthworms have many properties in antiperetic, antispasmodic, antidiuretic, antiasmatic, antihypertensive, antiallergic, anti-inflammatory, and have fibrinolytic activity. The purpose of this study was to determine the effect of the application of earthworm (Lumbricus rubellus) extract gel on the number of fibroblast cells in the gingival wound healing process of male Wistar (Rattus norvegicus) rats. Materials and Methods : This research method used in vivo laboratory experiments on wistar rats with three treatment groups, namely the group receiving 80% earthworm extract gel, and the control group giving placebo gel (CMC-Na 2%) which was observed on day 3. Results and Discussion: The results showed that there was a significant difference in the mean score of the number of fibroblasts on day 3 in the treatment group and the control group. The treatment group was given an 80% concentration of earthworm (Lumbricus rubellus) extract gel, which was 418.67, while the control group on day 3 was 270.33. Conclusion: It can be concluded that the gel extract of earthworm (Lumbricus rubellus) concentrate 80% is effective in increasing the number of fibroblast cells in the healing process of rat gingival wounds.

Research on the Design and Construction of Inclined Shafts for Long Mountain Tunnels: A Review

In recent years, inclined shafts have been widely used in long mountain tunnels, but the corresponding design and construction technical specifications need to be improved. By means of literature statistics and actual cases, a comprehensive and systematic review is made on the tunnel profile, lining structure, construction and operation ventilation, construction methods, and machinery of inclined shafts for long mountain tunnels. The results show that: (1) The design of a gentle slope section of an inclined shaft with large longitudinal slope needs to be further improved; (2) When an inclined shaft is only used for ventilation in the operation stage, it is necessary to make full use of the natural wind and eliminate its adverse effects; (3) It is suggested to study the supporting parameters of an inclined shaft in order to realize the standardised design of the supporting parameters; (4) The space of an inclined shaft is narrow, and it has practical demand in improving the automation, intelligence, management, and dispatching level of transport vehicles. In the future, it is an inevitable trend for electric vehicles to replace fuel vehicles. It is necessary to carry out further research on inclined shaft longitudinal slope design, construction and operation ventilation design, and transportation mode.

Nigella sativa L. seed extracts promote wound healing progress by activating VEGF and PDGF signaling pathways: An in vitro and in silico study

Background: A significant area of clinical research is the development of natural wound healing products and the management of chronic wounds. Healing wounds with medicinal plants has been a practice of ancient civilizations for centuries. Nigella sativa L (N. sativa) is a medicinal plant that has several pharmacological properties. Methods: The present study evaluated the wound healing properties of Nigella sativa L. (N. sativa) seed extracts using normal cell lines such as normal human dermal fibroblasts (NHDFs) and human umbilical vein endothelial cells (HUVECs). The expression levels of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) were analyzed through western blot analysis. Furthermore, computational analyses were carried out to screen the potential bioactive compounds for wound healing applications. Results: The results of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay revealed that, all the tested solvent extracts of N. sativa seeds (including ethanol, ethyl acetate, chloroform, and petroleum ether) did not exert any cytotoxic effects at the tested concentrations. Furthermore, the western blot analysis showed elevated levels of VEGF and PDGF upon treatment with N. sativa seed extracts. Gas chromatography-mass spectrometry (GC-MS) analysis of N. sativa extracts identified 268 phytocompounds. Molecular docking studies revealed that three phytocompounds of N. sativa extracts, including tricyclo[20.8.0.0(7,16)]triacontane, 1(22),7(16)-diepoxy-, adaphostin and obeticholic acid had strong binding affinity with wound healing-related target proteins, showing docking scores ranging from -5.5 to -10.9 Kcal/mol. These compounds had acceptable Absorption, Distribution, Metabolism, and Excretion (ADME) properties. Conclusions: Based on these results, N. sativa seed extracts might possess potential wound healing properties owing to the presence of a wide range of bioactive components.

HOXA3 accelerates wound healing in diabetic and aged non-diabetic mammals

Chronic wounds are characterized by a persistent, hyper-inflammatory environment that prevents progression to regenerative wound closure. Such chronic wounds are especially common in diabetic patients, often requiring distal limb amputation, but occur in non-diabetic, elderly patients as well. Induced expression of HoxA3, a member of the Homeobox family of body patterning and master regulatory transcription factors, has been shown to accelerate wound closure in diabetic mice when applied topically as a plasmid encased in a hydrogel. We now provide independent replication of those foundational in vivo diabetic wound closure studies, observing 16% faster healing (3.3 mm wounds vs 3.9 mm wounds at Day 9 post original injury of 6 mm diameter) under treatment with observable microscopic benefits. We then expand upon these findings with minimal dose threshold estimation of 1 μg HoxA3 plasmid delivered topically at a weekly interval. Furthermore, we observed similarities in natural wound healing rates between aged non-diabetic mice and young diabetic mice, which provided motivation to test topical HoxA3 plasmid in aged non-diabetic mice. We observed that HoxA3 treatment achieved complete wound closure (0 mm diameter) at 2 weeks whereas untreated wounds were only 50% closed (3 mm wound diameter). We did not observe any gross adverse effects macroscopically or via histology in these short studies. Whether as a plasmid or future alternative modality, topical HoxA3 is an attractive translational candidate for chronic wounds.

The Influence of Wind-Induced Response in Urban Trees on the Surrounding Flow Field

In recent years, cities have experienced frequent climate changes and deteriorating wind environments. Urban vegetation has become an important measure to improve local microclimates with its flexible configuration. Leaves and branches also reorient with the direction of wind, affecting the airflow through the tree. However, trees are usually considered as stationary porous media areas and are not influenced by wind speed in existing numerical simulation studies. Therefore, by considering the response of a tree under natural wind, this study established a fitted relationship between porosity and wind speed by measuring the porosity of trees at different wind speeds in the field. A numerical model of the wind response of the tree was developed, and the tree drag coefficient was changed using the additional source term method to verify the feasibility of the model by measuring the wind environment behind the tree. To understand the effect of the wind-induced response on the surrounding flow field and its variation pattern, the surrounding flow fields of stationary tree (T-S) and wind-induced tree (T-D) at different wind speeds were compared and analyzed. The effect of porosity and height-to-width ratio under the wind-induced response of trees on the wind environment were quantified. It was found that at different wind speeds, as the wind speed increases, the tree porosity gradually increases and the drag coefficient decreases accordingly. The effective shading distance after wind response was 2.4H, which was 0.3H less compared to vertically fixed trees. The minimum wind speed increased linearly with plant porosity, and the minimum wind speed occurrence location and wind speed recovery distance were linearly and negatively correlated with tree height-to-width ratio. Therefore, the flow field around the tree was simulated to provide references for guiding tree planting and mitigating urban wind environments.

Progress on research and mitigation of wind-blown sand risk in Dunhuang Singing Sand Mountain and Crescent Spring Scenic area, China

The Singing Sand Mountain and Crescent Spring Scenic Spot in Dunhuang, Northwest China is a world-renowned desert attraction that is also an integral component of the Dunhuang UNESCO Global Geopark. This scenic area underwent a 30-year transformation, i.e., from a severe sand risk with spring water threatened by sand burial due to dune deformation, to restoration of the original sand flow field and mitigation of the sand burial problem. The current paper summarizes the research on the intensive monitoring of the dynamic change of star dunes near the spring, observation of wind and sand flow movement, and then restoring the harmonic vibration of the sand particles (singing sand) that were previously silenced. The existing and prospective impacts of anthropogenic and natural forces on the deformation of the sand dunes are investigated by integrated methods, guiding the implementation of mitigating measures with significant ameliorative effects. Contrast to common sand control practices that aim to reduce wind speed and stop blown sands, our research highlights the importance of maintaining the natural wind flow field in stabilizing surrounding dunes. These mitigation measures consist of removing excessive vegetation and newly constructed buildings to recover the original wind flow field and sand transport activity. Such research and mitigation efforts ensure the scientific protection and restoration of the special desert landform, and contribute to the mutual enhancement of the conservation and exploitation of this desert scenic spot and similar sites.

Energy-neutral and socially inclusive abstraction of atmospheric CO2

A scheme is outlined for combating the overheated greenhouse effect by complementing measures to reduce CO2 generation by extracting CO2 at source and from the atmosphere. The gas is absorbed in sodium hydroxide (NaOH), as in many similar systems, but the process is powered by natural wind or solar pumps, the resulting Na2 CO3 and NaHCO3 are marketed, and fresh NaOH is generated mainly by electrodialysis of waste brine from solar desalination plants. The scheme could run at two main scales: domestic and industrial. The former requires integration into the social fabric, as has been waste recycling in the UK, the low CO2 extraction throughput to be compensated by the deployment of many millions of domestic units. The second scale is exemplified by CO2 traps mounted at favourable elevation, notably on some of the 350,000 major wind turbines operating worldwide. Atmospheric decarbonation would be complemented by CO2 trapping at its source, whether major, such as power stations, or minor but numerous, such as vehicles powered by fossil fuels.

Designing and testing the applicability of a natural green ventilation building block in an Egyptian Climatic zone using waste materials

Natural ventilation is one of the ways used to enhance building spaces' indoor air quality, especially after the COVID-19 pandemic. It also saves energy by utilizing natural wind forces to provide internal building spaces with fresh air instead of energy-consuming mechanical systems. For a multiple-floor building, adding external wall ventilation blocks can improve natural cross ventilation by catching and directing fresh air from the external prevailing wind into its internal spaces. This research aimed to enhance the building's natural ventilation by using environmentally friendly blocks. This was done by designing a green block using marble and granite waste materials as a partial substitute for conventional materials in the block. Styrofoam beads were added to the block’s mixture to reduce its weight. The block’s shape was designed to direct fresh air through building side walls by the use of natural wind pressure. The block was developed from the initial shape of the standard hollow block to a block with a wind catcher. Ventilation block shape simulations were done using (ANSYS fluent) computational fluid dynamics (CFD) software to determine the best inlet angle, catcher angle, and catcher length. The study revealed that by increasing the block inlet angle more than 45°, the block outlet air velocity starts to decrease due to the flow separation in the front part of the block inlet. The catcher angle ranged from 65° to 85°, and the catcher’s ability to redirect the airflow is decreased at a catcher angle greater than 85°. The best nondimensional catcher length-to-block length ratio (height /length) h/L was 0.625. Substitution of 5% of cement by granite in the presence of 0.15 Kg of Styrofoam (C5G) produced a lightweight green ventilation block of weight 19.3 kg. Whereas, the substitution of 15% of sand for marble in the presence of 1 Kg of Styrofoam (S15M) produced a lightweight green ventilation block of weight 15.9 kg. The produced block was tested in a building located in New Cairo City (a region currently having a tremendous increase in the building construction sector) as a study sample representing one of the Egyptian Climatic zones. The research concluded that it is preferred to allocate the building corners towards the prevailing wind direction to prevent airflow separation and to magnify the quantities of air along the building sides.

Understory plant growth forms respond independently to combined natural and anthropogenic disturbances

Natural disturbances can maintain forest diversity by creating a heterogeneous resource landscape, which can contribute to coexistence of early- and late-successional species. However, almost all forested ecosystems are also subject to multiple anthropogenic stressors, which could inhibit plant diversity and forest recovery after natural disturbances. Here, we present the first large-scale replicated field experiment testing the interactions among two natural and two anthropogenic disturbances in a mature secondary temperate forest. Specifically, we test the extent to which: 1. a natural windthrow (tornado), 2. deer browsing, 3. salvage logging, a common forestry practice to generate revenue after natural disturbances, and 4. mechanical removal of the understory, drive subsequent plant community assembly, diversity, and abundance. Our results have two clear messages. First, the combined disturbances, especially salvage logging, increased plant species richness and abundance; we found 65 more species in 0.1 ha of the disturbed areas versus the same area of reference forest. Second, we found that it was critical to analyze plant growth forms separately; each major plant growth form responded to the disturbances differently. Surprisingly, salvage logging, browsing, and vegetation removal had negligible effects on the diversity and abundance of tree seedlings or saplings. In contrast, salvaging increased herb richness by 30% (six extra species per 36 m2 plot), and shrubs were twice as abundant in salvaged versus unsalvaged plots. The combined disturbances created unique plant communities in comparison to adjacent undisturbed reference sites, but plant growth forms differed in which combination of disturbances shifted community composition the most. We did not find that non-native invasive species substantially increased in abundance in response to the disturbances, nor were invasive species unique to the salvaged areas. Together, our results demonstrate that a patchwork of combined natural and anthropogenic disturbances can promote plant diversity in a human-modified temperate forest. In particular, the combination of a natural wind disturbance and salvage logging benefited native herbaceous species, the plant group that represents the vast majority of vascular plant species (∼80%) in temperate forests across the world.

Aeroacoustic Vehicle Development Method Considering Realistic Wind Conditions

The aeroacoustic development of vehicles is still mainly carried out in wind tunnels under steady flow conditions, although the real situation is different. However, as discussed in several earlier publications, a vehicle experiences unsteady, turbulent flow on road, which results for example from natural wind, wakes of other vehicles, or obstacles at the roadside in combination with side wind. The resulting temporal variations of the wind noise inside the cabin affect the passengers' comfort and safety through fatigue. To be able to also consider the unsteady aeroacoustics in the vehicle development process, a comprehensive method has been developed that is presented in full for the first time in this paper. The on-road situation is simulated in a realistic and reproducible manner in the full-scale wind tunnel of the University of Stuttgart by means of an active turbulence generator, developed by FKFS. The turbulence generator allows to dynamically vary the flow angle with frequency components of up to 10 Hz. By comparing the unsteady wind noise for different flow situations and different vehicles, a flow scenario has been derived which leads to representative and meaningful aeroacoustic results. The measured temporal wind noise variations are investigated using modulation analysis, which has been adapted to show only relevant information in a comprehensible way. Finally, a psychoacoustic metric for rating the annoyance of unsteady, as well as steady, wind noise has been developed based on listening studies. The metric describes the subjective perception and allows evaluation and optimization of the aeroacoustic behavior specifically regarding the passengers' comfort. With this new method all wind noise aspects, steady as well as unsteady, can be determined and taken into account for vehicle development. The evaluation and comparison of vehicles and variants is comprehensive and is focused on the passengers' comfort.