White Elephants and Other Non-basic Commodities: Piero Sraffa and Krishna Bharadwaj on the Role and Significance of the Distinction between Basics and Non-basics

After the publication of Production of Commodities by Means of Commodities ( Sraffa, 1960 ), a lot of attention was devoted to ‘reswitching’, that is to the fact that a technique is cost-minimising at two disconnected ranges of the rate of profits and not so in between these ranges. We owe Krishna Bharadwaj (1970, Schweizerische Zeitschrift für Volkswirtschaft und Statistik, 106, 409–429) an important contribution to the debate by stating and proving a general result concerning the maximum number of switches between two techniques that have at least one switch point on the wage-frontier. She proved that the maximum number of switches coincides with the number of distinct commodities, without double counting, that enter directly or indirectly into at least one of the alternative methods of production. This means that if the alternative methods produce a commodity that is basic in both techniques, then non-basics in both techniques play no role in this, whereas if the alternative methods produce a non-basic commodity in at least one technique, then a role is played also by those non-basics that enter directly or indirectly into the production of at least one of the alternative methods of production. JEL Code: B12, B21, B31, B51, D24, D51

Calculation of the temperature distribution in heated switch points

Snow and ice can accumulate between the moveable parts of a switch point during the winter season. As a result he point cannot be switched anymore. In order to prevent failures and delays of trains, switch points are heated. Electrical heating rods shall ensure the melting of snow and ice in the critical areas of a point. Practical experiences have shown that this is not always possible. A calculation model for the heating of a point has to be set up in order to investigate the effectivity of switch point heating systems. Besides that, various ambient factors (such as ambient temperature, wind, precipitation) reduce the heating of the point. However, the extent of impact of the weather conditions on the heating remains to be investigated. Therefore, it is important to study their thermal influence and implement it into the calculation model. The Thermal Network Method (TNM) is suitable in this case. Initially the single main components of a switch point will be set up in separate networks. After a verification with experimental setups, the separate networks can be connected to each other. An experimental setup of an entire model point gives the opportunity to compare calculated and measured heating results without the influence of weather conditions. Finally, the ambient conditions can be implemented into the TNM model by performing field tests. The finished model can give high-resolution temperature information for different heating powers, ambient temperatures, wind velocities, rain and snowfall. According to the practical experience of various railway companies the temperature distribution is calculated for different parameter scenarios and subsequently evaluated regarding its effectivity to prevent failures.

A Dynamic Model for Limb Selection

Two experiments and a model on limb selection are reported. In Experiment 1 left-handed and right-handed participants (N = 36) repeatedly used one hand for grasping a small cube. After a clear switch in the cube’s location, perseverative limb selection was revealed in both handedness groups. In Experiment 2 the cubes were presented in a clockwise and counter-clockwise sequence to right-handed participant (N = 15). A spatial delay in the switch point between right-hand use and left-hand use was observed. The model simulates the experiments, by implementing the multiple-timescale dynamics of the action-selection process underlying limb selection. It integrates two mechanisms that were earlier proposed to underlie this selection aspect of manual activity: limb dominance and attentional information. Finally, the model is used to simulate Gabbard et al.’s (1997) experiment, offering a concise coupling of strength and direction of handedness.

Sensory conflict alters visual perception of action capabilities during crossing of a closing gap in virtual reality

The somatosensory, vestibular, and visual systems contribute to multisensory integration, which facilitates locomotion around obstacles in the environment. The joystick-controlled virtual reality (VR) locomotion interface does not preserve congruent sensory input like real-walking, yet is commonly used in human behaviour research. Our purpose was to determine if collision avoidance behaviours were affected during an aperture crossing task when somatosensory and vestibular input were incongruent, and only vision was accurate. Participants included 36 young adults who completed a closing gap aperture crossing task in VR using real-walking and joystick-controlled locomotion. Participants successfully completed the task using both interfaces. Switch point between passable and impassable apertures was larger for joystick-controlled locomotion compared with real-walking, but time-to-contact (TTC) was lower for real-walking than joystick-controlled locomotion. Increased joystick-controlled locomotion switch point may be attributed to incongruency between visual and non-visual information, causing underestimation of distance travelled towards the aperture. Performance on future VR applications incorporating dynamically changing gaps can be considered successful using joystick-controlled locomotion, while taking into account a potential behaviour difference. Differences in TTC may be explained by the requirement of gait termination in real-walking but not in joystick-controlled locomotion. Future VR studies would benefit from programming acceleration and deceleration into joystick-controlled locomotion interfaces.

Features of mathematical modeling of dynamic processes of car passing railroad turnouts

Dimensions and tolerances in the “wheelset — railway track” system are interconnected, since the normative values of geometric parameters and shape of the elements of the wheelsets and the track's upper structure are directly de pendent. In 2018– 2019 in order to establish the minimum permissible thickness of wheel flanges for freight cars in operation and to determine the influence of the thickness and shape of wheel flanges on the safe passage of turnout elements, JSC “VNIIZhT” conducted comprehensive stu dies, including the development of a methodo logy and mathematical modeling of the interaction of wheelsets and turnout elements. Features of modeling the dynamic proces ses of the entry of the first bogie of a freight car into the railway turnout when running to the side track are presented. The process of moving a freight car along the turnout is described de pending on the geometric parameters of the wheelset and track elements of the turnout, the position in the gauge of its first bogie before running into the switch point. Results of calculations of the lateral forces of the interaction of the wheelset and the turnout show that when running on, the maximum forces occurred during wheel impacts in the turnout elements, which depend on the conditions of the bogie entering the turnout. The initial position of the bogie and the peculiarities of its motion in the gauge determine the position of the meeting point and the value of the angle of incidence, their combination determines the maximum value of the force when moving to the lateral track, which, depending on the entry conditions, can differ by more than twice. Calculations showed that a change in the angle of inclination of the flange from 60 to 70° leads to a decrease in the safety factor of rolling stock on the turnout by 1.5 times. Required minimum value of the inclination of the wheel flange, ensuring safety (qR parameter), is determined by the creation of conditions that do not allow the wheel to run onto the tip of the switch point. Under existing norms of wear of turnout elements and the relative position of their rail elements, as well as taking into account the results of the calculations, the permissible value of qR should be in the range of 6.0...6.5 mm.