Reverse osmosis and forward osmosis fouling: a comparison

Our previously reported exploration (Journal of Membrane Science 565 (2018) 241–253) on the differences between fouling in reverse osmosis (RO) and forward osmosis (FO), used alginate as a foulant with initial conditions that ensured that the starting fluxes were the same. That study found that for a cellulose triacetate (CTA) membrane the extent of fouling, based on the analysis of foulant resistance, was greater when the membrane was part of a FO system. Herein, using the same methodology, results for a thin film composite membrane with alginate as the foulant are presented and these confirm the same general conclusion namely that the extent of foulant accumulation in FO mode is more severe than in RO mode. Furthermore the specific fouling resistance with alginate fouling in FO is more than for RO. However examining the overall operation including cleaning as well as fouling, this study suggests that FO operation is potentially less sensitive to fouling phenomena than RO for similar feed materials. This is due to the driving force compensation coming from a changing level of ICP. Some preliminary work including that with silica particles is also reported.

Study on the Influence of Triangular Groove Structure on Steady-State Flow Force Compensation Characteristics

In this study, a structurally improved spool was designed. The diameter of one side of the spool stem was reduced, making the spool stem into a rounded table shape. A triangular groove was circumscribed on the step and on the same side. After liquid flow was guided through the triangular groove, the flow direction changed. A flow component in the negative direction was generated, which reversely impacted the liquid flow in the positive direction. The liquid flow angle at the outlet increased; that is, jet angle increased and flow force decreased. The simulation results show that, increasing the depth, H, of the triangular groove has a positive effect on flow-force compensation and was conducive to the stability of the valve core. Properly increasing the groove’s bottom diameter, D1, of the triangular groove was conducive to the stability of the spool, but when D1 was too large, the flow force increased. The experimental results are consistent with the simulation results, which proves that the improved structure can effectively reduce the flow force of the spool.

Design and Analysis of a Flow-Control Valve With Controllable Pressure Compensation Capability for Mobile Machinery

There are the problems in the traditional pressure-compensation flow-control valve, such as low flow control accuracy, small flow control difficulty, and limited flow range. For this, a method of continuous control pressure drop Δprated (i.e. the pressure drop across the main throttling orifice) to control flow-control valve flow is proposed. The precise control of small flow is realized by reducing the pressure drop Δprated and the flow range is amplified by increasing pressure drop Δprated. At the same time, it can also compensate the flow force to improve the flow control accuracy by regulating the pressure drop Δprated. In the research, the flow-control valve with controllable pressure compensation capability (FVCP) was designed firstly and theoretically analyzed. Then the sub-model model of PPRV and the joint simulation model of the FVCP were established and verified through experiments. Finally, the continuous control characteristics of pressure drop Δprated, the flow characteristics, and flow force compensation were studied. The research results demonstrate that, compared with the traditional flow-control valve, the designed FVCP can adjust the compensation pressure difference in the range of 0∼3.4 MPa in real-time. And the flow rate can be altered within the range of 44%∼136% of the rated flow. By adjusting the compensation pressure difference to compensate the flow force, the flow control accuracy of the multi-way valve is improved, and the flow force compensation effect is obvious.

Position-insensitive estimation of mass from limit cycle of velocity feedback relay system with Spring

Mass measurement using relay feedback of velocity and restoring force compensation is investigated for determining the mass of an object under weightless conditions. In the measurement system, the velocity of the object is fed back through a relay with hysteresis and the force acting on the object is switched from a positive value to a negative value when the velocity reaches a positive threshold and vice versa. As a result, a limit cycle is induced in the measurement system and the mass is estimated based on the period of the limit cycle. In addition, restoring force compensation with a spring is introduced to avoid the drift of the trajectory. This compensation makes the static equilibrium state unique. However, the trajectory still drifts slightly. It causes some error in measurement when a simple formula of estimating mass is applied. To eliminate such an error, a new formula is derived to estimate the mass independently of the position of the trajectory that is determined by the switching positions in the relay actions. When the switching positions deflect from the origin at which the spring is in the natural length, the trajectory is not at the center and becomes asymmetric. It is analytically shown that the period of the limit cycle is minimum when the switching positions are at the origin. It indicates that mass is overestimated with the simple estimation formula when the trajectory is not at the center. The validity of the modified formula and the analytical results are confirmed experimentally.

Generation of static and dynamic small calibration forces and their measurements by electromagnetic force compensation balance

The paper presents some of the results of the static and dynamic force measurements at 100 nN to sub-10 µN ranges which are generated due the photon-momentum. The force sensor with resolution about 20 nN and operating in differential measurement mode is developed by two electromagnetic force compensation balances. In order to generate these calibration forces, CW lasers with different operational modes, power levels, and wavelengths are used. Multi-reflection configuration of the laser beam inside the macroscopic cavity with highly reflective mirrors are used to test and variate the total amount of the forces.

Investigations on nonlinear deformation phenomena in a force calibration system

Previous investigations show, in force calibration and measurement systems that are based on electromagnetic force compensation (EMFC), deformations of the flexure hinges can cause significant contributions to the uncertainty of the system. A Simulink model of the Planck-Balance 2 (PB2) is established in MATLAB according to the CAD model. <br />The results are compared to simplified analytical models and the results obtained from measurement.

Involving Sales Managers in Sales Force Compensation Design

Sales force incentive design often involves significant participation by sales managers in designing the compensation plans of salespeople who report to them. Although sales managers hold valuable territory-level information, they may benefit from misrepresenting that information given their own incentives. The author uses a game theoretic model to show (1) how a firm can efficiently leverage a manager’s true knowledge and (2) the conditions under which involving the manager is optimal. Under the proposed approach, the firm delegates sales incentive decisions to the manager within restrictive constraints. She can then request relaxed constraints by fulfilling certain requirements. The author shows how these constraints and requirements can be set to ensure the firm’s best possible outcome given the manager’s information. Thus, this “request mechanism” offers an efficient, reliable alternative to approaches often used in practice to incorporate managerial input, such as internal negotiations and behind-the-scenes lobbying. The author then identifies the conditions under which this mechanism outperforms the well-established theoretical approach of offering the salesperson a menu of contracts to reveal territory-level information.