Conceptual analysis of a four -stroke linear engine

During the past five years at West Virginia University, research into new auxiliary power generation devices has led to the development of a novel crankless reciprocating internal combustion engine. This dissertation presents a conceptual design of a Four-Stroke Linear Engine based on the numerical simulation of the operation of this type of linear engine. The engine consists of four opposed pistons linked by a connecting rod to a linear alternator. A series of numerical simulations was developed and employed to investigate the operation and performance of this crankless, four stroke linear engine. Since this linear engine is crankless, the numerical analysis of this particular engine is a time-based analysis. Two numerical models permit the simulation of the Four-Stroke Linear Engine employing Direct Injection Compression Ignition mode and a Homogeneous Charge Compression Ignition (HCCI) mode. The engine computational model combines dynamic and thermodynamic analyses. A detailed analysis of the engine operation range allows results to be obtained from a parametric study. The parametric study was performed to predict the engine behavior over a wide operating range, given intake parameters, variations in fuel combustion properties, reciprocating mass of the piston shaft assembly, frictional load and the externally applied load, and injection and valve timing. Based on the parametric study a conceptual design for a 15 kW linear engine was developed, showing the effects of reciprocating mass and air to fuel ratio on frequency of operation, power output, and efficiency. The engine analysis shown that this engine has a limited range of operation. The engine operating in as a direct injection compression ignition permitted high efficiency with values between 46 and 49% corresponding to a compression ratio range between 17 and 35.;The analysis performed for the engine operating as a HCCI mode revealed that this particular operating mode depends critically on the start of combustion, which depends in turn on piston motion which is not prescribed. Although the HCCI operation permitted to achieve high values of the efficiency (over 60%) and power output it was observed that the operation domain for the engine was much narrower than for the direct injection case. The results obtained from the numerical simulation show that the FSLE operating under HCCI is difficult to control and this observation extends to any mechanical arrangement of the linear engine with unconstrained piston motion

The Romanian Version of the Copenhagen Psychosocial Questionnaire – Short Report

AbstractWork related stress represents a characteristic of the present labour market and a health issue for both workers and organisations with major implications at the level of individuals, companies and society at large.As for Romania, according to statistical data published by the European Foundation for Improving the Working and Life Conditions, almost half of the workers in the active organisations of the Romanian labour market declare that their work is stressful. Although stress at work is claimed both by employers and employees, Romania does not have legislation to regulate explicitly at national, sectorial and enterprise level the safety and health at work policies and promote the wellbeing at work in relation to stress generating risks. Further on, the existing legislation does not specifically regulate the identification, evaluation and monitoring of the stress effects on the physical and mental health state. There are no practical validated instruments to identify, evaluate and monitor stress that can be used at the company level. A tool for the assessment of the psychosocial work environment – The Copenhagen Psychosocial Questionnaire (COPSOQ) – was adapted and validated in Romania in order to develop a standardized method to be used in research of the psychosocial factors and to assess the psychosocial work environment in different work areas in Romania.The main objectives of the study, part of a large ergonomic research, were: to adapt and validate the Romanian version of the COPSOQ. Adapting the original questionnaire and developing the Romanian version proved to be a necessary process, which was based on the translation and back translation method

Computational Models of Adult Neurogenesis

Experimental results in recent years have shown that adult neurogenesis is a significant phenomenon in the mammalian brain. Little is known, however, about the functional role played by the generation and destruction of neurons in the context of and adult brain. Here we propose two models where new projection neurons are incorporated. We show that in both models, using incorporation and removal of neurons as a computational tool, it is possible to achieve a higher computational efficiency that in purely static, synapse-learning driven networks. We also discuss the implication for understanding the role of adult neurogenesis in specific brain areas.Comment: To appear Physica A, 7 page

STRATEGIC ANALYSIS OF THE ROLE OF INTERNAL AUDIT IN OPTIMIZATION OF CORPORATE GOVERNANCE

The paper addresses the subject of corporate governance, including the elucidation of the peculiarities of the corporate governance aplication in entities from the corporate sector of the Republic of Moldova. It also analyses the role of internal audit within it.</p

In vivo measurement of afferent activity with axon-specific calcium imaging.

In vivo calcium imaging from axons provides direct interrogation of afferent neural activity, informing the neural representations that a local circuit receives. Unlike in somata and dendrites, axonal recording of neural activity-both electrically and optically-has been difficult to achieve, thus preventing comprehensive understanding of neuronal circuit function. Here we developed an active transportation strategy to enrich GCaMP6, a genetically encoded calcium indicator, uniformly in axons with sufficient brightness, signal-to-noise ratio, and photostability to allow robust, structure-specific imaging of presynaptic activity in awake mice. Axon-targeted GCaMP6 enables frame-to-frame correlation for motion correction in axons and permits subcellular-resolution recording of axonal activity in previously inaccessible deep-brain areas. We used axon-targeted GCaMP6 to record layer-specific local afferents without contamination from somata or from intermingled dendrites in the cortex. We expect that axon-targeted GCaMP6 will facilitate new applications in investigating afferent signals relayed by genetically defined neuronal populations within and across specific brain regions

Becoming a new neuron in the adult olfactory bulb

New neurons are continually recruited throughout adulthood in certain regions of the adult mammalian brain. How these cells mature and integrate into preexisting functional circuits remains unknown. Here we describe the physiological properties of newborn olfactory bulb interneurons at five different stages of their maturation in adult mice. Patch-clamp recordings were obtained from tangentially and radially migrating young neurons and from neurons in three subsequent maturation stages. Tangentially migrating neurons expressed extrasynaptic GABAA receptors and then AMPA receptors, before NMDA receptors appeared in radially migrating neurons. Spontaneous synaptic activity emerged soon after migration was complete, and spiking activity was the last characteristic to be acquired. This delayed excitability is unique to cells born in the adult and may protect circuits from uncontrolled neurotransmitter release and neural network disruption. Our results show that newly born cells recruited into the olfactory bulb become neurons, and a unique sequence of events leads to their functional integration

The Assessment of Mental Load of Air Traffic Controllers Based on Psychophysiological Indicators

The article presents a part of a broader study on identifying and monitoring occupational risks, early detection of signs and symptoms of reversible impairment of physical and mental health of staff, decrease in work capacity and the occurrence of deficient, risky behavior in working practices, as a result of intense neuropsychological or physical professional effort. The results of the study aimed at highlighting: professional effort factors experienced by the trial subjects; occupational risk factors that cannot be avoided and which, due to the nature of the workload and the conditions for completing it, can in time lead to reduced work capacity, premature wear and tear, work-related illnesses and risky behaviors in the workplace, with serious consequences for the safety and health of employees and / or other people; measures to prevent and reduce identified work and stress factors, in order to ensure health and safety at work, optimal use of human resources and maintenance of work capacity throughout the professional life. The results can be implemented in the actions taken to ensure occupational health and safety regulations and to monitor employees’ health conditions and their work capacity in accordance with the legislation in force. Document type: Articl