An enhanced circulating cooling water (CCW) machine is developed to simultaneously achieve high temperature stability and dynamic performance of CCW temperature control. Dynamic thermal filtering based on an auto-updatable thermal capacity medium is proposed to reduce the temperature fluctuation of the CCW. Agile thermal control is presented to realize a quick response and high resolution of temperature control, through thermal inertia minimization and bidirectional regulation of heating/cooling power. Experimental results indicate that a temperature stability of ±3 mK (peak to peak value) and a settling time of 128 s, corresponding to a 1 K step set value, are achieved. It can therefore be concluded that the developed machine can satisfy the challenging requirements of precision manufacturing.

The Demand for circulating cooling water (CCW) with high temperature stability and a quick response to temperature control is essential for precision engineering, so a dynamic thermal filtering method is proposed in this paper. Some CCW is bypassed, blocked, and used as a thermal capacity medium, and the temperature fluctuation of CCW is significantly reduced by heat exchanging with the medium. The temperature of the medium dynamically follows the set value of the CCW temperature by real time updating, and so realizes a quick CCW temperature control response. The attenuation ratio of temperature fluctuation was derived, theoretically validating the effectiveness of the method. The experimental results indicate that a CCW temperature fluctuation attenuation ratio of tens of dB (−3.47 dB, −6.91 dB, −10.97 dB and −15.28 dB corresponding to temperature fluctuation frequencies of 0.01 Hz, 0.025 Hz, 0.053 Hz and 0.105 Hz, respectively) is achieved by the proposed method. The updating time of thermal capacity medium is 82 s, which means that the temperature fluctuation attenuation remains functionally valid when the set value of CCW changes. The proposed method is low cost in operation and provides an effective approach to satisfy the challenging demand for CCW with high stability and a good dynamic temperature control performance.

A spherical scattering electrical-field probe(SSEP) with noncontact, 3D isotropy and approximate point probing characteristics has been proposed for high-precision measurement of micro and small structures with large aspect ratio. Development of signal processing circuits for detection of weak cpacitantive signal on sub-picofarad level is the key to realize nanometer resolution. In this paper, a set of signal processing circuits based on operational capacitance measurement principle is proposed, and characteristics of the circuits are theorically analyzed and optimized. Experimental results indicates that resolution of 1 nm and nonlinearity of6 nm are achieved with the proposed signal processing circuits for a SSEP with $\phi$ 2.5 mm probing ball.