Treatment of [Et 4 N][Tp*WS 3 ] (1) (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with [Cu-(MeCN) 4 ]PF 6 and NH 4 PF 6 (molar ratio = 1:2:1) in excess pyridine (py) produced one discrete trinuclear cluster [Et 4 N][Tp*WS 3 Cu 2 (py) 3 ](PF 6 ) 2 (2). Reactions of 1 with [Cu(MeCN) 4 ]PF 6 , NH 4 PF 6 , and 4,4′-bipyridine (4,4′-bipy) (or 1,2-bis(4-pyridyl)ethane (bpea)) (molar ratio = 1:2:1:2) afforded a two-dimensional (2D) [Tp*WS 3 Cu 2 ]-based cationic polymer {[Tp*WS 3 Cu 2 (4,4′-bipy) 1.5 ](PF 6 )•2MeCN} n (3•2MeCN) and a one-dimensional (1D) [Tp*WS 3 Cu 2 ]based cationic polymer {[(Tp*WS 3 Cu 2 ) 2 (bpea) 3 ]-(PF 6 ) 2 •2DMF} n (4•2DMF), respectively. Analogous reactions of 1 with CuCN, NH 4 PF 6 , and 4,4′-bipy (or 1,2-bis(4pyridyl)ethylene (bpee)) (molar ratio = 1:2:1:2) gave rise to a 2D [Tp*WS 3 Cu 2 ]-based polymer {[Tp*WS 3 Cu 2 (μ-CN)(4,4′bipy) 0.5 ]•MeCN} n (5•MeCN) and a three-dimensional (3D) [Tp*WS 3 Cu 2 ]-based anionic polymer {[Et 4 N][(Tp*WS 3 Cu 2 ) 2 {Cu-(μ-CN) 2.5 } 2 (bpee)]•3MeCN} n (6•3MeCN), respectively. Compounds 2−6 were characterized by elemental analysis, IR, UV−vis, 1 H NMR, and single-crystal X-ray diffraction. The cluster cation of 2 has a butterfly-shaped [Tp*WS 3 Cu 2 ] core structure in which one [Tp*WS 3 ] unit binds two Cu atoms via one μ 3 -S and two μ-S atoms.3 consists of one 2D (6,3) network in which butterfly-shaped [Tp*WS 3 Cu 2 ] units are interlinked by the 4,4′-bipy ligands. 4 contains butterfly-shaped [Tp*WS 3 Cu 2 ] units that are interconnected by bpea bridges to form one 1D zigzag chain. 5 holds another 2D (6,3) network in which the 1D [{Tp*WS 3 Cu 2 } 2 (μ-CN) 2 ] n chains are bridged by 4,4′-bipy ligands. 6 possesses a 3-connected 3D (10 3 ) anionic net in which each 2D [{(Tp*WS 3 Cu 2 ) 2 Cu 2 (μ-CN) 4 } 4 (μ-CN) 4 (bpee) 2 ] n 4n− network is interlinked to its neighboring ones via pairs of bpee ligands. The isolation of 2−6 with unstable [Tp*WS 3 Cu 2 ] cores may be ascribed to the coordination of N-donor ligands or linkers at Cu(I) centers of these cores and the formation of polydimensional [Tp*WS 3 Cu 2 ]-based frameworks (in the case of 3−5). The third-order nonlinear optical (NLO) properties of 2−6 in DMF were also investigated by using a femtosecond degenerate fourwave mixing (DFWM) technique at 800 nm.
Dissolved oxygen (DO) concentration is a key variable in wastewater treatment process (WWTP). It directly influences effluent quality of a wastewater treatment. However, due to the great changes of the influent flow rate and the large uncertainties of the wastewater in composition, concentration, and temperature, most control approaches become powerless on DO regulation. To improve the robustness of a DO control, and reduce the phase delay between the control input and the system output, a U-model-based active disturbance rejection control (UADRC) is proposed. The U-model control (UC) reduces the phase delay between the control input and the system output. The active disturbance rejection control (ADRC) enhances the robustness of the closed-loop system. Also, ADRC converts the system dynamics to be integrators connected in series, which helps the realization of UC. By changing the system dynamics to be an approximate unit, a controller based on desired closed-loop system dynamics can be designed and the DO concentration is guaranteed. UADRC combines advantages of both UC and ADRC, and a commonly accepted benchmark simulation model no.1 (BSM1) is taken to verify the proposed UADRC. Numerical results show that, with similar energy consumption, the UADRC is able to achieve much better tracking performance than ADRC, SMC, and PI with suggested parameters.
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