Assessment of Gearbox Operational Loads and Reliability under High Mean Wind Speeds

AbstractThis paper investigates the dynamic loads occurring in the drivetrain of wind turbines with a focus on offshore applications. Herein a model of the gearbox of the 5 MW wind turbine is presented. The model is developed in a multi-body framework using commercial software MSC ADAMS. Validation of the model was based on the experimental data provided by NREL for 750kW prototype gearbox. Failures of gearboxes caused by high dynamic loads have a significant influence on the cost of operation of wind farms. For these reasons in the study, the probability of failure of the gearbox working in an offshore wind turbine that operates in storm conditions with mean wind speeds less than 30 m/s is presented. In the study, normal shut-downs of a wind turbine in storm conditions were investigated. The analysis were conducted for two storm control strategies and different wind conditions from an extreme operating gust, normal turbulence model and extreme turbulence model. In the paper, loads in the planetary gear are quantified as well as the torsional moments in the main shaft. On the basis of simulation results the annual probability of failure of the gearbox in a wind turbine with soft storm controller is calculated, and compared with the one had the gearbox working in a wind turbine operating with hard storm controller. In the study, it was found that normal shut-downs do not have a significant influence on the ultimate loads in the gearbox, since they are related mostly to the gusts occurring during turbulence. Application of the storm controller with reduction of the wind turbine power allowed the decrease of the probability of failure for ultimate stresses

Measuring consumers' engagement with brand-related social-media content: development and validation of a scale that identifies levels of social-media engagement with brands

The main purpose of this study is to develop a scale to measure consumer's engagement with social media brand-related content. The reported scale (CESBC) comprises three dimensions: consumption, contribution, and creation. Qualitative techniques were used to generate an initial pool of items that capture different levels of consumer engagement with social media brand-related content. Quantitative data from a consumer survey (=2252) was then collected in two phases to calibrate and validate the ensuing scale. Results confirmed the structure and psychometric properties of the CESBC. As expected, each subscale is significantly correlated with nomological network constructs, i.e., brand equity and brand attitudes

Active shooters — how close are they?

Recent terrorist attacks in the United States, Canada and Western Europe have shown an increase in the incidence of “Active Shooters” [1]. These ruthless and desperate assassins usually attack urban and poorly protected areas (lack of armed protection) that are densely populated [2]. Utilizing their strength, they realize that their plan is to maximize the number of casualties, without counting on the consequences of their actions. The basis of their action may be based on extremely radical views. Frequent outcomes for active shooters include suicide during an attack (90%) or the resolution of the threat by the authorities [3]. In response to the ever-increasing number of assassinations and the risk of such incidents in one’s immediate surroundings, comprehensive education should be widely spread. Thus, it is important to promote appropriate behaviour, rules of reaction during an attack by an armed assailant, as well as cooperation with incoming service personnel. Such actions will not only help one prevent, but also allow one to prepare for such incidences

Family dairy farms in the Podlasie province, Poland: farm typology according to farming system

The aim of this paper is to establish a farm typology according to the dairy farming systems in the western part of the Podlasie province. Data of 39 variables was collected by a survey to owners of 123 family farms. A two-stage multivariate analysis was conducted in order to determine farm typology. Three principal components were detected, explaining 80.4% of the total variance. The cluster analysis identified five groups of farms. In two groups the cow productivity is the biggest in the area. A third group contains the smallest and lowest cow productivity farms, with high proportion of non-agricultural activities. One of the two remaining groups has better soil quality and medium cow productivity. The other group has low or medium soil quality but cow productivity is higher than in the fourth group. The SWOT analysis shows different weaknesses and strengths for different groups, as well as those common to a larger number of groups. Weaknesses are related to small farm size, large number of workers, low or medium soil quality and low or medium level of technology. Strengths are related to a large share of fodder crops, low livestock density, diversification of agrarian activities and acceptable cow productivity. On the other hand, general opportunities are linked to the EU-CAP evolution and to the presence of cooperatives in the region, whereas general threats derive from a hypothetic increase of feed prices and quantity of milk produced in the EU, which could lead to a fall in milk prices.El objetivo de este trabajo es establecer tipologías de sistemas lecheros en el oeste de Podlasia (Polonia). Se analizaron 39 variables a partir de encuestas realizadas a propietarios de 123 explotaciones. Tras el análisis multivariante en dos etapas (factorial y cluster) se encontraron tres componentes principales que explican el 80,4% de la varianza total y se obtuvieron cinco grupos de explotaciones. En dos de los grupos la productividad de las vacas es la mayor de la zona. Un tercer grupo tiene las granjas más pequeñas y menos productivas, con una mayor proporción de actividades no agrarias. El cuarto tiene los suelos de mejor calidad y una productividad de las vacas media y el quinto tiene suelos de calidad media o baja pero una productividad de las vacas superior. En general, las debilidades están relacionadas con una escasa dimensión de las granjas, un elevado número de trabajadores, una baja o media calidad de los suelos y un bajo o mediano nivel de tecnología. Las fortalezas están relacionadas con la abundancia de cultivos forrajeros, una carga ganadera baja, una aceptable diversificación agraria y una aceptable productividad de las vacas. Las principales oportunidades están ligadas a la evolución de la PAC de la UE y a la presencia de cooperativas para la comercialización de la leche. Las principales amenazas derivan de los posibles incrementos de precios de los alimentos para el ganado y de leche producida en la UE, que puede conducir a una caída de los precios de venta de la leche

TACTICAL MEDICINE INSPIRING CIVILIAN RESCUE MEDICINE IN THE MANAGEMENT OF HAEMORRHAGE

   Accidents remain to be the most common cause of death amongst men of ages 10–39 and women of ages 5–24. The sudden occurrence of simultaneous multiple events or a mass casualty event with many patients suffering severe injuries, including severe haemorrhage, requires emergency medical personnel to modify the algorithms, which dictate their actions. The military war mission in Iraq and Afghanistan brought many experiences, which were used and applied to guidelines, which are now used for the management of patients experiencing trauma in the civilian sector. The current trauma ITLS (International Trauma Life Support) guidelines suggest to use compression bands or haemostatic dressings in order to control bleeding in case of massive haemorrhage. An example of this recommendation being used can be seen in the regional par­amedic station in Poznan, Poland, where each ambulance is outfitted with “rescue packages” to be used in the event of massive haemorrhage. This practice can also be seen in Great Britain as well as Germany, where local protocols recommend the use of medical equipment taken from tactical medicine. The use of such tools allows for achieving a greater chance of rapid and effective haemostatic control in the event of massive haemorrhaging. These tools allow for more efficient use of time at the scene of the event, reducing the time a patient spends at the scene, allowing more rapid transport to hospital and more specialised surgical support. Reducing the time spent at the scene of an event while carrying out important procedures such as stabilising the patient’s airway, stopping haemorrhage and immobilising the patient, markedly improves the survival of trauma patients

Development of a spray-ejector condenser for the use in a negative CO2 emission gas power plant

One promising solution for developing low-emission power technologies is using gaseous fuel combustion in pure oxygen when the exhaust gas mixture is composed of H2O and CO2, and where CO2 is separated after steam condensation. The paper presents the results of computational analyses providing to the Spray-Ejector Condenser (SEC) development, which is one of the crucial components of the negative CO2 gas power plant (nCO2PP) cycle development. The proposed design of the ejector-condenser to ensure the high effectivity of vapor condensation and CO2 compression with preparation to separation, ready for application in gas power cycle, is a novelty of this research. Different computational techniques leading to the development and better understating of ejector operation were applied. The main operating conditions in the characteristic connected with the developed nCO2pp cycle points were investigated to evaluate the impact of the operating conditions on SEC performances. The amount of motive water needed for the cooling purpose is susceptible to the inlet water pressure and temperature and strongly affects the generated pressure of the suction stream. The preliminary results confirm that the SEC's basic design and geometrical dimensions can be applied in the negative CO2 power plant cycle. Results from CFD modeling give the possibility to investigate the turbulent flow of water/steam/CO2 mixture together with the condensation process occurring at this same time. It is found that the average droplet diameter and motive water supplying method significantly effects the condensation intensity. The further direction of the presented computational research activities and results is to test various designs of Spray-Ejector Condensers that will enable the evaluation of the direct contact condensation process and develop the final geometrical design. © 2023 The AuthorsDevelopment of a spray-ejector condenser for the use in a negative CO2 emission gas power plantpublishedVersio

The effect of social media communication on consumer perceptions of brands

Researchers and brand managers have limited understanding of the effects social media communication has on how consumers perceive brands. We investigated 504 Facebook users in order to observe the impact of firm-created and user-generated social media communication on brand equity, brand attitude and purchase intention by using a standardized online survey throughout Poland. To test the conceptual model, we analyzed 60 brands across three different industries: non-alcoholic beverages, clothing and mobile network operators. When analyzing the data, we applied the structural equation modeling technique to both investigate the interplay of firm-created and user-generated social media communication and examine industry-specific differences. The results of the empirical studies showed that user-generated social media communication had a positive influence on both brand equity and brand attitude, whereas firm-created social media communication affected only brand attitude. Both brand equity and brand attitude were shown to have a positive influence on purchase intention. In addition, we assessed measurement invariance using a multi-group structural modeling equation. The findings revealed that the proposed measurement model was invariant across the researched industries. However, structural path differences were detected across the models

Market knowledge and new product performance: the mediating effects of new product creativity

Market knowledge is recognised as an important predictor of new product performance, which existing studies have proven. However, a missing link in this relationship is creativity, and specifically, as a natural process in product innovation. This study aims to examine a model that includes two mediating mechanisms between market knowledge scope and two new product outcomes, respectively: a new product’s competitive advantage and its commercial success. In both cases two mediators are used that represent dimensions of creativity—i.e. a product’s meaningfulness and novelty. The model was tested on a sample of 374 Polish medium-high- and high-technology companies using structural equation modelling. The results indicated that market knowledge is transferred to both new product outcomes through new product creativity, albeit somewhat differently. The first mediating mechanism, which explains the factor of competitive advantage, operates only through the indirect effects of both the product’s meaningfulness and its novelty. The second mechanism works directly, through the market knowledge’s effect on commercial success, as well as indirectly, through product meaningfulness. Subsequently, theoretical and managerial implications as well as indications for future research are provided based on these findings