Search results for "tabu"
showing 10 items of 180 documents
Alpu kreimules herbāriji Latvijas Universitātes Muzejā
1922
Alpu kreimule Pinguicula alpina L. ir rets augs, kurš šobrīd vairs nav sastopams Latvijas flora. Tā vienīgā dabīgā augtene bija uz Staburaga Daugavas krastā. Pļaviņu HES būvniecibas rezultātā tā tika iznīcināta. Latvijas Universitātes Muzeja herbārijā Botānikas un mikoloģijas kolekcijās glabājas šā auga herbāriji gan no Latvijas, gan Igaunijas. Šeit atrodas gan senākais ievāktais herbārijs uz Staburaga, gan pēdējais, kas tika šeit ievākts 1961. gadā.
Adaptive memory programing for the robust capacitated international sourcing problem
2008
The International Sourcing Problem consists of selecting a subset from an available set of potential suppliers internationally located. The selected suppliers must meet the demand for items from a set of plants, which are also located worldwide. Since the costs are affected by macroeconomic conditions in the countries where the supplier and the plant are located, the formulation considers the uncertainty associated with changes in these conditions. We formulate the robust capacitated international sourcing problem by means of a scenario-optimization approach. When dealing with uncertainty, one of the most common approaches in the literature is to formulate the problem via a set of possible …
Scatter Search and Path Relinking: Foundations and Advanced Designs
2004
Scatter Search and its generalized form Path Relinking, are evolutionary methods that have been successfully applied to hard optimization problems. Unlike genetic algorithms, they operate on a small set of solutions and employ diversification strategies of the form proposed in Tabu Search, which give precedence to strategic learning based on adaptive memory, with limited recourse to randomization. The fundamental concepts and principles were first proposed in the 1970s as an extension of formulations, dating back to the 1960s, for combining decision rules and problem constraints. (The constraint combination approaches, known as surrogate constraint methods, now independently provide an impo…
Traumatic damage to the cartilage influences outcome of anatomically reduced acetabular fractures: A medium-term retrospective analysis
2011
We reviewed 77 patients with an acetabular fracture, treated operatively through a non-extensile approach after an average time of 45 months. The ilioinguinal approach was chosen in 41, the Kocher-Langenbeck approach in 36 patients. Following the Letournel classification, the most frequent lesions were posterior wall (26%), two-column (22.1%) and anterior column (14.3%) fractures. Subchondral impaction, intra-articular fracture fragments and fracture comminution, called modifiers, could be identified in the preoperative CT-data of 38 patients (49.4%). Patients were operated after an average of 4 days. Average hospital stay was 19 days. Sciatic nerve and peroneal nerve palsy were registered …
Hip Muscle Strength Recovery after Hip Arthroscopy in a Series of Patients with Symptomatic Femoroacetabular Impingement
2014
International audience; Purpose: The aim of the study was to prospectively evaluate hip muscle strength in a series of patients with symptomatic FAI after hip arthroscopy. Methods: Hip muscle strength of eight patients (age: 29 +/- 10 years) was evaluated preoperatively and 2.5 years after hip arthroscopy, and was compared to eight matched controls. Maximal voluntary contraction (MVC) strength was measured for all hip muscle groups. At follow-up, we used the symptom-specific well-being outcome to assess the acceptability of the health state related to the hip. Results: Patients showed MVC strength increases for all hip muscles (9-59%, P<.05). At follow-up, only hip flexor MVC strength was l…
Bilateral ureteral obstruction and renal failure caused by massive retroperitoneal hematoma: is there a pelvic compartment syndrome analogous to abdo…
1998
Objectives: To describe an intrapelvic compartment syndrome analogous to abdominal compartment syndrome and to characterize its diagnosis and treatment. Design: Retrospective analysis. Setting: Level I trauma center. Patients: Three patients with pelvic ring or acetabular fractures presented with bilateral ureteral obstruction, renal organ failure. and anuria due to direct compression of both ureters in the true pelvis by a massive retroperitoneal hematoma, Intervention: Surgical therapy consisted of fracture stabilization, decompression of the retroperitoneal space, and evacuation of the hematoma. Persistent isolated bleeding points were either embolized preoperatively or ligated. Results:…
Quantitative computed tomography-assisted osteodensitometry of the pelvis after press-fit cup fixation: a prospective ten-year follow-up.
2011
Background: As a follow-up of a previously reported three-year study, we analyzed the periprosthetic acetabular cortical and cancellous bone density changes at ten years after implantation of a press-fit cup. Methods: Prospective clinical, radiographic, and quantitative computed tomography examinations were performed within ten days and at mean periods of one, three, and ten years after total hip arthroplasty with a press-fit cup, a femoral stem with a tapered design, and alumina-alumina pairing. Periacetabular cortical and cancellous bone density (mg CaHA/mL) in the cranial, ventral, and dorsal regions about the cup were measured for twenty-four hips in vivo. Results: All acetabular cups s…
Postrenal anuria in pelvic or acetabular injury: a report of three cases.
1996
Renal failure due to obstruction by a retroperitoneal hematoma is a rarely discussed complication in pelvic or acetabular fractures. Three cases of this obstructive uropathy are presented. They were successfully treated with removal of the hematoma and draining of the retroperitoneal space.
Heuristics and meta-heuristics for 2-layer straight line crossing minimization
2003
AbstractThis paper presents extensive computational experiments to compare 12 heuristics and 2 meta-heuristics for the problem of minimizing straight-line crossings in a 2-layer graph. These experiments show that the performance of the heuristics (largely based on simple ordering rules) drastically deteriorates as the graphs become sparser. A tabu search metaheuristic yields the best results for relatively dense graphs, with a GRASP implementation as close second. Furthermore, the GRASP approach outperforms all other approaches when tackling low-density graphs.
Tabu and Scatter Search for Artificial Neural Networks
2003
In this paper we address the problem of training multilayer feed-forward neural networks. These networks have been widely used for both prediction and classification in many different areas. Although the most popular method for training these networks is back propagation, other optimization methods such as tabu search or scatter search have been applied to solve this problem. This paper presents a new training algorithm based on the tabu search methodology that incorporates elements for search intensification and diversification by utilizing strategic designs where other previous approaches resort to randomization. Our method considers context and search information, as it is provided by th…