Accuracy and precision: A new viewon kinematic assessment of solid-state hinges and compliant mechanisms

Compliant mechanisms are alternatives to conventional mechanisms which exploit elastic strain to produce desired deformations instead of using moveable parts. They are designed for a kinematic task (providing desired deformations) but do not possess a kinematics in the strict sense. This leads to difficulties while assessing the quality of a compliant mechanism’s design. The kinematics of a compliant mechanism can be seen as a fuzzy property. There is no unique kinematics, since every deformation need a particular force system to act; however, certain deformations are easier to obtain than others. A parallel can be made with measurement theory: the measured value of a quantity is not unique, but exists as statistic distribution of measures. A representative measure of this distribution can be chosen to evaluate how far the measures divert from a reference value. Based on this analogy, the concept of accuracy and precision of compliant systems are introduced and discussed in this paper. A quantitative determination of these qualities based on the eigenvalue analysis of the hinge’s stiffness is proposed. This new approach is capable of removing most of the ambiguities included in the state-of-the-art assessment criteria (usually based on the concepts of path deviation and parasitic motion).

A multi-patient analysis of the center of rotation trajectories using finite element models of the human mandible

Studying different types of tooth movements can help us to better understand the force systems used for tooth position correction in orthodontic treatments. This study considers a more realistic force system in tooth movement modeling across different patients and investigates the effect of the couple force direction on the position of the center of rotation (CRot). The finite-element (FE) models of human mandibles from three patients are used to investigate the position of the CRots for different patients’ teeth in 3D space. The CRot is considered a single point in a 3D coordinate system and is obtained by choosing the closest point on the axis of rotation to the center of resistance (CRes). A force system, consisting of a constant load and a couple (pair of forces), is applied to each tooth, and the corresponding CRot trajectories are examined across different patients. To perform a consistent inter-patient analysis, different patients’ teeth are registered to the corresponding reference teeth using an affine transformation. The selected directions and applied points of force on the reference teeth are then transformed into the registered teeth domains. The effect of the direction of the couple on the location of the CRot is also studied by rotating the couples about the three principal axes of a patient’s premolar. Our results indicate that similar patterns can be obtained for the CRot positions of different patients and teeth if the same load conditions are used. Moreover, equally rotating the direction of the couple about the three principal axes results in different patterns for the CRot positions, especially in labiolingual direction. The CRot trajectories follow similar patterns in the corresponding teeth, but any changes in the direction of the force and couple cause misalignment of the CRot trajectories, seen as rotations about the long axis of the tooth.

Looking for Options to Sustainably Fixate Nitrogen. Are Molecular Metal Oxides Catalysts a Viable Avenue?

Fast and reliable industrial production of ammonia (NH3) is fundamentally sustaining modern society. Since the early 20th Century, NH3 has been synthesized via the Haber–Bosch process, running at conditions of around 350–500°C and 100–200 times atmospheric pressure (15–20 MPa). Industrial ammonia production is currently the most energy-demanding chemical process worldwide and contributes up to 3% to the global carbon dioxide emissions. Therefore, the development of more energy-efficient pathways for ammonia production is an attractive proposition. Over the past 20 years, scientists have imagined the possibility of developing a milder synthesis of ammonia by mimicking the nitrogenase enzyme, which fixes nitrogen from the air at ambient temperatures and pressures to feed leguminous plants. To do this, we propose the use of highly reconfigurable molecular metal oxides or polyoxometalates (POMs). Our proposal is an informed design of the polyoxometalate after exploring the catabolic pathways that cyanobacteria use to fix N2 in nature, which are a different route than the one followed by the Haber–Bosch process. Meanwhile, the industrial process is a “brute force” system towards breaking the triple bond N-N, needing high pressure and high temperature to increase the rate of reaction, nature first links the protons to the N2 to later easier breaking of the triple bond at environmental temperature and pressure. Computational chemistry data on the stability of different polyoxometalates will guide us to decide the best design for a catalyst. Testing different functionalized molecular metal oxides as ammonia catalysts laboratory conditions will allow for a sustainable reactor design of small-scale production.

Functional Capacity of Patients with Advanced Gastrointestinal and Breast Cancer Pre-treatment - a Cross-Sectional Comparison to Healthy Age-matched Women

Purpose: The aim of the study was to compare the functional status of patients with advanced gastrointestinal and breast cancer prior treatment to healthy age-matched volunteers. Methods: In this 3-arm cross-sectional study female patients with advanced cancer (UICC ≥ III) (gastrointestinal: n=17; 68.4±5.6years; BMI: 24±5.1kg/m2; breast: n=17; 64.1±7.8years; BMI: 23.6±3.7kg/m2) before first-line chemotherapy and 17 healthy age-matched women (68.6±5.8years; BMI 24.6±3.2kg/m2) were included. The functional status was assessed using the short physical performance battery (SPPB). A capacitive force platform was used for gait speed recordings during free level walking. Maximal isometric voluntary contraction force (MIVF) of the quadriceps muscle was assessed by a strain gauge force system. Body composition was obtained from bioelectrical-impedance-analysis. Physical activity was assessed via accelerometry. Results: Compared to the healthy controls and to patients with breast cancer, gastrointestinal cancer patients have lower values in the SPPB (10.4±1.3vs.8.9±2.0 vs.6.8±2.6; p<.01), phase angle (5.4±0.5°vs.5.2±0.5°vs.4.5±0.8°; p<.01), MIVF (8.8±1.9vs.9.2±3.5vs.6.0±2.1N/kg; p<.01), and gait speed (5.0±0.6vs.4.6±0.5vs. 3.6±1.1km/h; p<.01). The daily steps were significantly lower in gastrointestinal cancer patients compared to healthy women (3407±2408;8774±3975, p<.01).Conclusions: Already prior treatment patients with advanced gastrointestinal cancer have a reduced functional status compared to breast cancer patients and healthy controls. Gait speed, phase angle and MIVF are below cut-off values for a low prognosis of survival. This physical deconditioning prior treatment might influence the toxicity of the therapy. Thus, supportive interventions to improve the functional status and to support the treatment in patients with advanced gastrointestinal cancer seems to be of high concern.Trial Registration: Registered study at ClinicalTrials.gov (NCT02677129).

Mechanical force system of double key loop with finite element analysis

Background The mechanics of double key loop (DKL) are not well defined, and this finite element study was designed to explore its force system. Methods A simplified 3-dimensional finite element model of single and double key loops with an archwire between the lateral incisor and second premolar was established in Ansys Workbench 17.0. Activation in Type-1 (retraction at the distal end), Type-2 (retraction at the distal key) and Type-3 (Type-2 plus ligation between keys) was simulated. The vertical force, load/deflection ratio and moment/force ratio of stainless-steel and titanium-molybdenum alloy (TMA) loops were calculated and compared. Results The double key loop generated approximately 40% of the force of a single key loop. Type-2 loading of DKL showed a higher L/D ratio than Type-1 loading with a similar M/F ratio. Type-3 loading of DKL showed the highest M/F ratio with a similar L/D ratio as single key loop. The M/F ratio in Type-3 loading increased with the decreasing of retraction force. The DKL of TMA produced approximately 40% of the force and moment compared with those of SS in all loading types. When activated at equal distances below 1 mm, the M/F ratios of SS and TMA DKL with equal preactivation angles were almost the same. Conclusion The M/F ratio on anterior teeth increases with the preactivation angle and deactivation of DKL. The M/F ratio at a certain distance of activation mainly depends on the preactivation angle instead of the wire material. TMA is recommended as a substitute for SS in DKL for a lower magnitude of force.

Modeling of deformation of the bimaterial with thin Non-linear interface inclusion

An incremental approach to solving the antiplane problem for bimaterial media with a thin, physically nonlinear inclusion placed on the materials interface is discussed. Using the jump functions method and the coupling problem of boundary values of the analytical functions method we reduce the problem to the system of singular integral equations (SSIE) on jump functions with variable coefficients allowing us to describe any quasi-static loads (monotonous or not) and their influence on the stress-strain state in the bulk. To solve the SSIE problem, an iterative analytical-numerical method is offered for various non-linear deformation models. Numerical calculations are carried out for different values of non-linearity characteristic parameters for the inclusion material. Their parameters are analyzed for a deformed body under a load of a balanced concentrated force system.

Validación de un dispositivo Wireless para el control de variables cinemáticas en el rendimiento deportivo

Validar un dispositivo Wireless para el censo de la aceleración en actividades deportivas. Para la validación se usó un transductor lineal (T-Force System Ergotech) y análisis de videografía (SkillSpector ). Participantes desarrollaron el press de banca plana en una maquina SMITH. El protocolo consistió en realizar una repetición de press de banca plana con una carga constante (18 kg). La recuperación entre cada repetición fue de 15 segundos. En total 5 sujetos desarrollaron 84 repeticiones. Los datos estuvieron caracterizados por una diferencia menor entre los valores de la media del dispositivo Wireless vs T-Force (0,18) en contraste con Wireless vs Videografía (0,46). Los resultados muestran que no existen diferencias estadísticamente significativas en la aceleración de desplazamiento entre el dispositivo Wireless, transductor lineal y análisis de videografía; sin embargo, los niveles de correlación de Pearson que se reportaron manifestaron una asociación moderada (p<0,05) para las dos pruebas. El supuesto de independencia de los errores fue contrastado mediante la prueba de Durbin-Watson. Los resultados sugieren que, si bien no se presentaron altas asociaciones entre los dispositivos, el factor económico de la producción del dispositivo Wireless, lo hace una alternativa viable para el control y medición de la aceleración en la práctica deportiva.

Generate Various Parameters Of Trv Envelope Synthetic Test Circuit

The most basic transient a circuit breaker needs to suffer during its activity is the transient recovery voltage (TRV), started by the electric force system as a characteristic response on flow interference. To test high voltage CBs, direct testing utilizing the force system or short out alternators are not practical. The testing of high voltage Circuit Breakers (CBs) of bigger limit requires huge limit of testing station. An equal infusion of short out current and transient voltage to medium and high voltage circuit breaker (CB) by a synthetic model is examined. Transient recovery voltage is made by a capacitor bank and is applied to CB. An optical set off spark gap has been utilized to interrupt short circuit and to introduce of transient recovery voltage that is applied across the contacts of circuit breaker. Transient recovery voltage examination can never be done totally, as the advancement of circuit breaker development and organization configuration goes on. The most widely recognized way to deal with TRV examination is concerning the supposed planned TRV, in which a suspicion of dismissing association between circuit breaker itself and the innate system recovery voltage is being made. Notwithstanding, it actually is by all accounts qualified to examine what circuit breaker means for transient recovery voltage. An ideal grouping to open/close of reinforcement test article and helper circuit breakers inside suitable chance to infuse of recovery voltage. The impact of reactance of inductive flaw current limiter just as distance to blame in short line issue condition on pace of ascent of recovery voltage. A 4-boundaries TRV synthetic test circuit dependent on equal current infusion technique is planned and mimicked for testing 145kV rating circuit-breakers according to new TRV prerequisites given in IEC 62271-100.