HYDRAULIC CHARACTERISTICS OF PARTIAL OPENING OF THE WORKING GATE FOR A DISCHARGE TUNNEL

The partial opening of the working gate for a discharge tunnel is used more and more widely in the various conditions, such as releasing discharge to meet the needs of the various stages under construction, or of the operations at low reservoir levels. In this article the hydraulic characteristics were investigated of the partial opening of the working gate based on the physical model experiments of the discharge tunnel for the Longtan Hydropower Project, including the discharge coefficient, the surface profile of the free flow section, the bottom pressure distribution of the tunnel with an aerator, the cavity length just from the ramp, and the wall pressure of the curve section of the outlet. Some new issues were discussed and the properties were presented of the partial opening of the gate.

Open Partial Nephrectomy: One Night Length of Stay Is Safe and Cost Effective

Objective: To review our open partial nephrectomy (OPN) experience and compare to known robotic partial nephrectomy (RPN) data to determine whether length of stay (LOS) and morbidity are significant drivers in the surgical approach employed for partial nephrectomy. Methods: We reviewed our OPN experience during the last 3 years examining age, tumor size, LOS, pathology, blood loss, complications, recurences, and deaths. Results: Seventy-five patients underwent OPN during this period. Mean age was 59 years, tumor size 2.8 cm, percent malignant 75%, estimated blood loss 350 cc. With a median follow-up of 18 months, there was one urinoma managed by drain-age, one pseudo aneurysm that required embolization and one pulmonary embolism that required anticoagulation. There were no readmissions, no tumor recurences, and no deaths. Our major complication rate was 4% as compared to other trials that re-ported major complication rates between 1% - 9% for RPN and between 3% - 24% for OPN. In the first half of the experience (n = 37), median LOS was 57 hours. Using a pathway encouraging early ambulation and smaller incisions in the second half of the experience (n = 38), median LOS was 35 hours. This is much shorter than reported RPN LOS of 62 - 67 hours and OPN LOS of 108 - 142 hours. Conclusion: OPN can be performed safely and effectively with one night hospital stay. This provides a more cost-effective approach to partial nephrectomy with similar or better complication rates and calls into question the main value drivers of RPN.

Mathematical Model of a Hyperbolic Hydraulic Fracture with Tortuosity

The aim of the research is to study the propagation of a hydraulic fracture with tortuosity due to contact areas between touching asperities on opposite crack walls. The tortuous fracture is replaced by a model symmetric partially open fracture with a hyperbolic crack law and a modified Reynolds flow law. The normal stress at the crack walls is assumed to be proportional to the half-width of the model fracture. The Lie point symmetry of the nonlinear diffusion equation for the fracture half-width is derived and the general form of the group invariant solution is obtained. It was found that the fluid flux at the fracture entry cannot be prescribed arbitrarily, because it is determined by the group invariant solution and that the exponent n in the modified Reynolds flow power law must lie in the range 2 < n < 5. The boundary value problem is solved numerically using a backward shooting method from the fracture tip, offset by 0 < δ ≪ 1 to avoid singularities, to the fracture entry. The numerical results showed that the tortuosity and the pressure due to the contact regions both have the effect of increasing the fracture length. The spatial gradient of the half-width was found to be singular at the fracture tip for 3 < n < 5, to be finite for the Reynolds flow law n = 3 and to be zero for 2 < n < 3. The thin fluid film approximation breaks down at the fracture tip for 3 < n < 5 while it remains valid for increasingly tortuous fractures with 2 < n < 3. The effect of the touching asperities is to decrease the width averaged fluid velocity. An approximate analytical solution for the half-width, which was found to agree well with the numerical solution, is derived by making the approximation that the width averaged fluid velocity increases linearly with distance along the fracture.

Long-term oncologic outcomes of laparoscopic versus open partial nephrectomy

Background Most of the literatures on laparoscopic partial nephrectomy （LPN） versus open partial nephrectomy （OPN） focus on technical details and early or mid-term oncologic outcomes, reflecting that the approach is safe and provides mid- term benefits compared with traditional open surgery. However, the difference of long-term oncologic outcome between LPN and OPN remains unclear. The aim of this meta-analysis was to evaluate the long-term oncologic outcome of LPN in the treatment of localized renal tumors compared with that of OPN. Methods A systematic search of electronic databases including Medline, Embase, and Cochrane library was conducted. Comparative studies reporting on long-term oncologic outcome of LPN versus OPN were regarded eligible. The odds ratio （OR） and its corresponding 95% confidence intervals （CO were calculated for the oncologic outcomes. The methodologic quality of the included studies was evaluated using the strict criteria of the Newcastle-Ottawa scale. Results Six comparative studies （1495 participants including 555 LPN and 940 OPN） were included in the present study. There was no significant difference between LPN and OPN in 5-year overall survival （OS） rates （OR=1.83, 95% Cl （0.80, 4.19））, 5-year cancer specific survival （CSS） rates （OR=1.09, 95% CI （0.62, 1.92））, and 5-year recurrence free survival （RFS） rates （OR=0.68, 95% CI （0.37, 1.26））. Conclusion The results of this meta-analysis revealed that there was no significant difference in long-term oncologic outcome between LPN and OPN for treatment of localized renal tumors.

Flow choking characteristics of slit-type energy dissipaters

In this paper, the behavior of the flow choking, including the critical and developing states, was experimentally investiga- ted by means of five slit-type outlets, characterized by the outlet width, the contraction angle and the opening of the working gate. The results showed that the approach flow Froude number of the critical choking decreases if the outlet width increases, or the con- traction angle decreases, or the opening increases. There is the hysteresis when the flow choking develops, i.e., the Froude numbers of the appearance and disappearance of the flow choking at the increasing discharge regime are all larger than those at the decreasing discharge regime. For various widths of the outlets, the differences between the critical Froude numbers at small opening are much larger than thoset at large opening. The change range from appearance to disappearance of the flow choking at small opening is smaller than that at large opening.