Search Results (18)

User churn in online games refers to players becoming inactive for an extended period. Even a small increase in churn can lead to significant revenue loss, making churn prediction crucial for sustaining long-term player engagement. Although user churn prediction has been extensively studied, most existing approaches either ignore non-login periods or treat all inactivity uniformly, overlooking key behavioral differences. This study addresses this gap by categorizing non-login periods into three types, as follows: inactivity due to new or dormant users, genuine loss of interest, and temporary inaccessibility caused by external factors. These periods are treated as either non-existent or missing data and imputed using techniques such as mean or mode substitution, linear interpolation, and multiple imputation by chained equations (MICE). MICE was selected due to its ability to impute missing values more robustly by considering multivariate relationships. A random forest (RF) classifier, chosen for its interpretability and robustness to incomplete data, serves as the primary prediction model. Additionally, classifier chains are used to capture label dependencies, and principal component analysis (PCA) is applied to reduce dimensionality and mitigate overfitting. Experiments on real-world MMORPG data show that our approach improves predictive accuracy, achieving a micro-averaged AUC of above 0.92 and a weighted F1 score exceeding 0.70. These findings suggest that our approach improves churn prediction and offers actionable insights for supporting personalized player retention strategies. Full article

This research explores the two-phase flow behavior involved in enhanced dense phase carbon dioxide inactivation of E. coli DH5α, which has been shown to possess a high microbial reduction efficiency of up to 3.7 ± 0.4 log. We present an experiment in which the liquid sample was pressurized with liquid carbon dioxide to 8.2 MPa and, after saturation, was forced to flow through a mini tube. An experimental setup was developed to visualize the flow patterns (plug, slug and churn flows) occurring in the mini tube by means of high-speed imaging. The values of the wall shear stress were estimated within the mini tube with the help of the gas slug velocities (8–9 m/s) and were compared with threshold shear stress values reported for the disruption of fresh E. coli cells. The results suggest that the preliminary pressurization phase may cause a substantial destabilization of the cell wall of E. coli DH5α. Full article

Reverse osmosis (RO) is known for the economic dewatering of dairy streams without any change in phase. At the household level, surplus milk is fermented and churned to obtain butter, which is subsequently heated to obtain clarified milk fat (ghee). The production of 1 kg ghee generates 15–20 kg sour buttermilk (SBM) as a by-product that is mostly drained. This causes a loss of milk solids and environmental pollution. The processing, preservation and valorization of SBM are quite challenging because of its low total solids (TS) and pH, poor heat stability and limited shelf life. This investigation aimed to transform SBM into a novel dried dairy ingredient. SBM was thermized, filtered, defatted and concentrated at 35 ± 1 °C, employing RO up to 3.62× (12.86%). The RO concentrate was subsequently converted into sour buttermilk powder (SBMP) by employing spray drying. SBMP was further characterized for its physicochemical, reconstitution and functional properties; rheological and morphological characteristics; and amino acid and fatty acid profiling, along with FTIR and XRD spectra. SBMP was “instant soluble-3 s” and exhibited excellent emulsion stability (80.70%), water binding capacity (4.34 g/g of protein), flowability (28.36°) and antioxidant properties. In nutshell, a process was developed for the valorization of sour buttermilk to a novel dairy ingredient by employing reverse osmosis and a spray-drying process. Full article

Electronic sports show significant user churn caused by a toxic gaming atmosphere, and current GUI-based interventions are insufficient to address the issue. Based on the theoretical framework of Perceiving and Experiencing Fictional Characters, a new hybrid interaction interface and paradigm combined with tangibles is proposed to counter negative mood. To support the frustrated users of Massive Online Battle Arena (MOBA) games, we added AI teammates for better personal performance and social robots for the disclosure of negative mood. We hypothesized that AI teammates’ invisibility and anonymity would mitigate negative emotions; an effect amplified by the presence of social robots. A comparative experiment was conducted with 111 participants. Social robots for emotion-oriented coping improved user mood but AI teammates for problem-oriented coping did so better, although their higher levels of experienced anonymity may not have been preferred. Unexpectedly, conversing with a robot after playing with an AI teammate brought the mood back to that experienced when talking to a robot alone, while increasing the distancing tendencies. With this in mind, AI and social robots can counter the negative atmosphere in MOBA games, positively contributing to game design and empathic human–computer interaction. Full article

The term churning is defined by a multifaceted approach and is quite a complex concept that has been gaining relevance in the field of human resources, due to the problematic loss of investment, originating from the voluntary exits of worker-associated costs. This phenomenon is a direct result of the rising competitive job market, causing employees to leave organizations and carry with them all the knowledge and experience acquired in the starting organization, an organization which invested in the development of its workers. Even though churning is aligned with human resource practices, it is considered a multifaceted concept because of the different contexts in which it interferes, such as economic context, per activity sector, clients, the type of organization, geographic location, etc. Although, despite its own complexity, churning is related to turnover; however, there are differences between these two concepts. While turnover is linked to the workers’ rotation within an organization, churning is mainly focused on the costs associated with voluntary exits from workers. It is simply linked to investment losses inside an organization, which has the main goal of creating mechanisms that allow the creation of awareness in organizations about the relevancy of action using strategic measurements of holding in order to minimize the churning rate, and in this way, reducing the unexpected costs, creating revenue, increasing proficiency, standing out in business activity, bettering nimbleness and expanding profits. This initial manuscript introduces the churning concept in human resources, the main causes of churning, as well as approaching how organizations take action in order to appease this event using literature, which lacks major advertising and given relevance to its pertinence in human resources. Through the analysis of the existing, this entry was guided with the objective of demystifying the subject of human resource churning. Full article

The present study was conducted in Portugal and had, as its object of study, workers from Portuguese companies belonging to several sectors of activity. The main goal of this study was the identification of the dimensions related to the causes of churning and to analyse its applicability in the management of human resources to promote individual and corporate welfare. Its specific targets were (a) to make a sociographic characterisation of the workers; (b) to make their professional characterisation; (c) to analyse the perception workers had in relation to the selected dimensions under study. Through the gathering of data per questionnaire, a sample consisting of 801 answers was considered. First, we resorted to a multivariate statistical analysis through the application of an Exploratory Factor Analysis (EFA) that allowed for the selection of the most relevant dimensions, followed by a descriptive statistical analysis on the collected sample and used items. Finally, we resorted to a TwoStep Cluster analysis that allowed for the identification of two Clusters of workers with a differentiated probability for the occurrence of churning. Full article

The present study has, as its objective, the construction and validation of a scale of causes of churning. Through both literary review and the results obtained through the performance of interviews in a previous study, a scale composed of 35 items was elaborated. This scale was applied online, through Google Forms, via Linkedin Corporation in the period ranging from June to September 2021. The validity of the scale was conducted through first and second order factor analysis so to confirm its hierarchical structure. After validation by exploratory factor analysis (n = 349), its structure was verified, and the model was subsequently adjusted by confirmatory factor analysis (n = 452) using structural equations. The reliability and internal consistency of the instrument was also tested with values in all dimensions above 0.7. Thus, it is concluded that this new instrument holds nine items and three dimensions, which possesses acceptable validity and reliability, and can be used to diagnose the causes of churning of human resources. Full article

As a result of the complexity and multiplicity of definitions of the concept of human resource churning, to guide this entire research, the cost resulting from replacements was taken as a premise. Although churning is related to turnover, there are differences, turnover has as its focus the turnover of workers and churning is also related to the same approach, but this concept has as its focus the costs associated with the replacements of workers derived from voluntary departures, i.e., churning is only related to the costs of hiring from replacements. Despite the complexity and multiplicity of definitions of the concept of churning, to guide the present research, we chose to adopt as our premise the costs resulting from the voluntary exits of workers, that is, the relationship between resulting costs associated with employee substitutions. The present investigation intended to identify the causes of churning through the identification of its main dimensions. This theoretical research resorted to the following methodology: a literature review and an empirical study review that approached the subject of the churning of human resources. The resulting outcome enabled us to identify how these dimensions had an influence on the management of human resources regarding the mitigation of the occurrence of churning and the application of strategic measures to retain workers. In this regard, we have identified as main dimensions the work environment; leadership; recognition; schedule flexibility; wage; career progression, responsibility, and retention of human resources. Full article

As an essential component in the offshore oil and gas industry, subsea jumpers are likely to encounter the cyclic-induced stresses caused by the alternating movement of gas plugs and liquid slugs while transporting a multiphase mixture. The present study investigates the gas-liquid flow and the induced vibration in a multi-plane jumper by adopting experimental and numerical techniques. The flow patterns at every characteristic section of a Z-shaped jumper with an inner diameter of 48 mm are experimentally investigated, including dispersed bubbly, slug, churn, wavy, stratified and annular flows. Displacement and pressure sensors are installed near each elbow to record the vibration and pressure response of the jumper. It is found that both pressure characteristics and vibration amplitudes are highly related to the gas content rate, mixing velocity, and gas and liquid superficial velocity. The one-way fluid–solid coupling numerical simulations are performed and validated against the experimental data in terms of the flow patterns and the induced vibrations at different gas–liquid velocities. The results reveal that both simulated flow patterns and vibration responses agree well with the experiments. Full article

Since the clearance between the guide rail and the roller reduces the efficiency of the 2D pump, this paper proposes a novel 2D piston pump with stacked taper roller sets to eliminate the effect of the clearance. The structure of the 2D pump is introduced, and the mathematical model of the torque and the mechanical efficiency of the bilateral force on the guide rail are established and analyzed. The model takes into account the change in the oil viscosity, the spatial angle and the oil churning loss. A test rig was built to test the mechanical efficiency under different operating conditions. The unilateral and bilateral force models of the guide rail were compared, which proved that the bilateral force model of the guide rail can predict the mechanical efficiency more accurately than the unilateral force model. In the case of high load pressure, there was a clearance between the test results and the model calculation results. It is speculated that the main reason for this is that the greater oil pressure causes the size of the contact area between the two taper rollers and between the taper roller and the guide rail to become larger. The resulting rolling friction coefficient becomes larger, which affects the mechanical efficiency. Full article

The objective of the study was to compare the buttermilk released from the churning of sweet cream separated from sheep milk (BSM) or whey (BSW) with the buttermilk from sweet cow milk cream (BCM). Additional experimental factors were the heat treatment (68 °C for 10 or 30 min) and storage of cream (refrigeration or freezing). The composition of BSM was the most advantageous in terms of non-fat solids, protein—which was the most abundant solid component—casein, calcium and phosphorus contents. No significant differences were observed in the phospholipids (PL) content of BSM, BCM and BSW. Antioxidant potential and emulsion stability (ES) of BSM were the highest. The radical scavenging activity (RSA) of BSW was high opposite to chelating activity (CA). Some functional properties of BSW were similar to those of BSM and BCM. The freezing of cream affected the churning, the fat content, the soluble nitrogenous fraction at pH 4.6 (WSN) and some functional properties of buttermilk, but not in a consistent manner. The properties of BSM were marginally affected or unaffected by the use of frozen cream. The freezing of whey cream caused significant changes (p < 0.05) in the protein profile and the functional behaviour of BSW. Cream heat treatment affected the WSN of BSW opposite to its sweet cream counterparts. Full article

Given the current socio-economic context in which the labor market is set in, if we were to consider both employment opportunities in specific economic periods and the individual expectations workers have regarding one’s working conditions, it should be a matter of one’s individual right of choice to decide whether or not to stay or leave and change companies. The paper we present before you took into account the phenomenon of churning as a cyclical process. Our main goal was to understand the main causes leading to it in the context of human resources and, ultimately, what were the consequences emerging from it. In order to carry out this analysis, we put forward a conceptual-theoretical model of the phenomenon of churning, made possible through the analysis of both the currently available literature and the empirical studies and conclusions stemming from the latter. The aforementioned analysis allowed us to trace all main causes responsible for the origin of churning and also, to understand how it could be implemented further on, in order to minimize the costs associated with hiring new personnel and retaining qualified employees by resorting beforehand to the implementation of strategic measures of human resources retention. By applying the methodology based on grounded theory, this study allowed us to further contribute to the already available, yet limited, literature and definition of this multifaceted and greatly complex subject that is the phenomenon of churning. Full article

The manufacturing development of axial piston pumps usually takes the trend of high speed and miniaturization, and increases power density. Axial piston pumps are usually characterized as high speed to improve the power density; thus, high-speed churning losses caused by the internal rotating components stirring the oil can increase significantly. In order to improve the efficiency, more attention should be given to the churning losses in axial piston pumps, especially in high-speed conditions. Using the method of least-squares curve fitting, this paper establishes a series of formulas based on the churning losses test rig over a wide range of speeds, which enable accurate predictions of churning losses on the cylinder block and pistons. The reduction coefficient of flow resistance of multi-pistons as calculated. The new churning losses formula devoted to the cylinder block and rotating pistons was validated by comparison with experimental evidence in different geometries of axial piston pumps. According to the prediction model of churning losses, some valuable guidance methods are proposed to reduce the energy losses of the axial piston pump, which are the theoretical support for the miniaturization of axial piston pump manufacturing. Full article

In recent years, two dimensional (2D) hydraulic components have significantly flourished. After a brief development introduction of the 2D pump and 2D flowmeter, it could be concluded that the churning loss, which is caused by the rotational motion of 2D motion-converting mechanisms, has an increasing effect on reducing energy losses. This paper first presents a new 2D motion-converting mechanism and introduces its structure and working principles. To compare it with the former 2D motion-converting mechanism, the same working conditions were applied when designing the new one. Afterward, the generated churning loss by the active parts of the mechanism, such as the new rotor, was well studied by establishing a simplified CFD simulation model and was also verified to have a smaller churning loss than that of the former mechanism. As another key simulation result, the influence of the axial motion of the new rotor was found to be negligible for the churning loss even when the rotational speed was high enough. A test rig was subsequently built up to prove the simulation by monitoring the torque at various rotational speeds. As a result, the churning losses that took place in the new 2D motion-converting mechanism were certainly reduced, and the potential reasons for that were analyzed, as shown in the conclusion section. Full article

The imbalanced distribution of shared bikes in the dockless bike-sharing system (a typical example of the resource-sharing system), which may lead to potential customer churn and lost profit, gradually becomes a vital problem for bike-sharing firms and their users. To resolve the problem, we first formulate the bike-sharing system as a Markovian queueing network with higher-demand nodes and lower-demand nodes, which can provide steady-state probabilities of having a certain number of bikes at one node. A model reduction method is then designed to reduce the complexity of the proposed model. Subsequently, we adopt an operator-based relocation strategy to optimize the reduced network. The objective of the optimization model is to maximize the total profit and act as a decision-making tool for operators to determine the optimal relocation frequency. The results reveal that it is possible for most of the shared bikes to gather at one low-demand node eventually in the long run under the influence of the various arrival rates at different nodes. However, the decrease of the number of bikes at the high-demand nodes is more sensitive to the unequal demands, especially when the size of the network and the number of bikes in the system are large. It may cause a significant loss for operators, to which they should pay attention. Meanwhile, different estimated values of parameters related with revenue and cost affect the optimization results differently. Full article