Search

To measure the magnitude of the effect of the infarct location measured using the posterior circulation Alberta Stroke Program Early Computed Tomographic Score (pc-ASPECTS) on the functional outcome at 90 days in patients with basilar artery (BA) occlusion undergoing endovascular therapy (EVT).Of the acute ischemic stroke patients undergoing EVT for acute posterior circulation large vessel occlusion enrolled in the multicenter observational registry from December 2013 to February 2021, patients with BA occlusion were included. A favorable outcome was defined as achieving a modified Rankin Scale score of 0-3 at 90 days. The effect of pc-ASPECTS including the distribution on favorable outcomes was evaluated.One hundred patients were analyzed. Fifty-one patients (51%) achieved favorable outcome. Patients achieving a favorable outcome were younger, had a lower National Institutes of Health Stroke Scale score before EVT, and had a higher pc-ASPECTS before EVT than those not achieving a favorable outcome. Multivariable logistic analysis showed a significant association between higher pc-ASPECTS and a favorable outcome (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.02-1.52; p = 0.028). Considering the infarct location, bilateral cerebellar infarction was significantly associated with a lower frequency of favorable outcomes than those without cerebellar infarction (OR 0.16; 95% CI 0.04-0.51; p = 0.002).A higher pc-ASPECTS before EVT could be a predictor of a favorable outcome after EVT for BA occlusion. In particular, the presence of bilateral cerebellar infarction before EVT was significantly associated with a lower likelihood of a favorable outcome.

Patients with Coronavirus disease 2019 (COVID-19) who receive extracorporeal membrane oxygenation (ECMO) tend to show extreme hypercoagulability and require intensive anticoagulant therapy. The prognosis is extremely poor in patients with intracranial hemorrhage. We report a case of COVID-19 complicated by acute subdural hematoma, which necessitated craniotomy for hematoma evacuation to improve the patient's prognosis. A 60-year-old man diagnosed with COVID-19 presented with severe respiratory failure and hypercoagulability and underwent ECMO along with intensive anticoagulant therapy with a large dose of heparin. Physical examination revealed anisocoria secondary to acute subdural hematoma. He denied a history of head injury, and computed tomography angiography revealed no vascular lesions. We diagnosed the patient with a non-traumatic, simple type hematoma. We discussed this case with the attending physician and reviewed the surgical indications and procedures. The attending physician recommended postoperative heparin withdrawal with ECMO. The hematoma was evacuated using a small crani-otomy. Considering the risk of COVID-19, we cautiously performed all intraoperative procedures, especially those associated with aerosol generation, such as irrigation and the use of the craniotome. Heparin was discontinued postoperatively. The modified Rankin scale (mRS) score on postoperative day 90 was mRS 3. Optimal infection control measures prevented nosocomial infections in this patient despite the emergency surgical intervention.

To investigate the associations of perioperative P2Y12 reaction units (PRU) measured using VerifyNow with ischemic and bleeding events, and to determine the PRU threshold in the setting of elective neuro-endovascular treatment (EVT) for intracranial/extracranial vascular disease in patients taking aspirin and clopidogrel.Of the patients undergoing elective neuro-EVT while taking aspirin and clopidogrel, those taking both antiplatelet agents for 7 days or more and whose PRU and aspirin reaction units (ARU) were measured were included. The primary and safety outcomes were defined as symptomatic ischemic and major bleeding events within 30 days after EVT.A total of 197 patients were available for the analyses. Higher PRU was associated with symptomatic ischemic events on multivariable logistic analysis (odds ratio per 10 increase 1.14 [95% confidence interval 1.03-1.27], p=0.011). Receiver operating characteristic curve analysis showed that PRU ≥212 was the threshold to predict symptomatic ischemic events (area under the curve=0.73; sensitivity, 62.5%; specificity, 82.0%). Lower PRU was also associated with major bleeding events (odds ratio per 10 increase 0.87 [0.78-0.96], p=0.004), and the threshold to predict major bleeding events was PRU ≤46 (area under the curve=0.76; sensitivity, 70.0%; specificity, 87.2%) CONCLUSIONS: The PRU value was associated with symptomatic ischemic and major bleeding events after elective neuro-EVT in patients taking aspirin and clopidogrel. PRU ≥212 and PRU ≤46 appeared to be the threshold values to predict symptomatic ischemic and major bleeding events, respectively.

BACKGROUND An awake surgery is a useful measure to remove tumors located close to eloquent areas of the brain to reduce surgical complications and maximize the resection. However, it has some disadvantages compared to surgeries under general anesthesia. Generally speaking, applying it to a child under 15 years-old (y/o) is hesitating because of anxiety, poor tolerance, failure to cooperate in tasks and so forth. Here, we present a case of a 13y/o girl who underwent an awake surgery due to dysembryplastic neuroepithelial tumor (DNT) located in the left parietal lobe. CASE PRESENTATION: She consulted our hospital for epileptic seizures. MRI showed a multilocular mass lesion in the left parietal lobe. The tumor was located in or close to eloquent areas. The epilepsy was refractory even with multiple antiepileptic drugs (AEDs). A Wada examination revealed that her speech area is on the left hemisphere. The operations were performed in two stages. Prior to the operations, we had several thought-out simulations in the operating room and ICU with her, her parents, and our staff including nurses and lab technicians. The first operation was to perform tumor biopsy and place intracranial electrodes. The histological diagnosis was DNT. Video electroencephalogram showed that the epileptogenic lesion was around the tumor. The second operation resulted in total tumor resection and reduction of paroxysmal epileptic spikes without major complications. She is seizure free for more than three years with two AEDs. CONCLUSION Careful preparations may enable an awake surgery even for a child under 15y/o.

BACKGROUND Central nervous system germinoma occurs most often in early teens, accounting for 15% of childhood brain tumors. Here, we report a case of germinoma which recurred in the spinal cord 13 years after complete remission. CASE DESCRIPTION: A 15-year-old boy presented with diabetes insipidus (DI). MRI showed a pineal gland tumor and ventriculomegaly. Biopsy was performed and the histological examinations revealed PLAP and c-kit positive pure germinoma. Ki67 LI was 64.4%. Gamma knife radiosurgery and 3 courses of ICE chemotherapy brought disappearance of the tumor. However, it recurred in lateral ventricles. Forty-Gray whole brain radiation resulted in complete remission of the tumor. For the sake of DI treatment and MRI examinations, he kept periodical visit to our hospital. Thirteen years later, when he was 28y/o, he complained paresthesia in the right upper extremity. MRI demonstrated gadolinium-enhance mass lesion in the cervical spinal cord. Recurrence of the tumor and multiple sclerosis were the principal differential diagnosis. Pulse steroid therapy did not make any change, and radiation therapy to the cervical spinal cord led to tumor disappearance. Nevertheless, the tumor recurred on the dorsal medulla oblongata one and a half years later. Biopsy of the tumor clarified that the tumor was germinoma. ICE chemotherapy which was limited to three courses due to severe bone marrow suppression was carried out. MRI proved no enhanced mass lesion in the central nervous system. DISCUSSION Germinoma may recur even after long period of remission, demonstrating that long-term follow-up is indispensable.

Introduction: Interhospital transfer to endovascular-capable centers (ECCs) is reported to correlate with worse clinical outcome after endovascular stroke reperfusion therapy (ESRT). The aim of this study was to investigate the relationship between admission mode and functional outcome after ESRT in real clinical setting in Japan. Methods: The RICOVERY study retrospectively registered 575 patients with large vessel occlusion who were admitted to and underwent ESRT at 16 ECCs in Ibaraki prefecture, located just northeast of Tokyo, within 24 hours of onset between January 2015 and December 2017. We extracted patients without in-hospital stroke onset or recurrence and divided them into two groups: those with interhospital transfer (I group) and with direct admission to ECCs (D group). Favorable outcome (FO) was defined as a mRS of 0-2 at discharge. We additionally performed a subgroup analysis with patients with premorbid mRS of 0-2 and who underwent ESRT within 6 hours of onset. Results: A total of 483 patients (198 women, 75±11 years) was included. Intravenous thrombolysis was performed in 289 patients (60%). In the I group (n=69), median baseline NIHSS score was lower (17 vs 19, p=0.025) and the proportion of large-artery atherosclerosis was higher (19% vs 10%, p=0.025) compared with the D group (n=414). The rates of reperfusion (mTICI grade 2b/3) were similarly high in both groups (88% and 86%, respectively). Although median onset-to-puncture time (OPT) was longer in the I group than in the D group (240 min vs 185 min, p=0.01), no significant difference was shown in the rate of FO between the groups (28% vs 36%, p=0.197). In subgroup analysis, baseline NIHSS scores and stroke subtypes were similar between the I group (n=51) and the D group (n=273). Median OPT was longer in the I group than in the D group (220 min vs 160 min, p=0.005) as with the entire study cohort, and the rate of FO in the I group was lower than in the D group (24% vs 43%, p=0.01). After multivariate adjustment, interhospital transfer was a negative predictor of FO (Odds ratio, 0.343; 95% confidence interval, 0.158-0.747). Conclusion: In this Japanese real-world study, interhospital transfer was associated with delays of ESRT and lower chance of FO within a 6-hour time window.

BACKGROUND Pediatric brainstem gliomas rarely occur and are a heterogeneous group of diseases, which increases the difficulty of treatment strategy. Here, we present a case of pediatric pontine glioma treated with Gamma Knife surgery (GKS) after open biopsy. CASE DESCRIPTION: An 11-year-old boy presented with diplopia due to the left MLF syndrome. MRI showed a well-circumscribed, protruding tumor with partial gadolinium enhancement in the dorsal pons. An open biopsy was performed via the suprafacial triangle following midline suboccipital approach. Histological examinations revealed high cellularity and mild atypia. Immunohistochemistry demonstrated positive stain for GFAP and Olig2 antibodies, and negative for p53 protein. The Ki67-labeling index was 6.8%. Pyrosequence analysis indicated IDH1/2 wild type (wt), BRAF V600 wt, H3F3A K27 wt, FGFR1 wt, and TERT wt. The final diagnosis was pediatric diffuse astrocytoma, WHO grade II, pons. GKS was performed one month after the biopsy. After transient worsening of the symptom, it disappeared gradually. The tumor is stable for three years with mild shrinkage of the size. DISCUSSION: Gross total resection (GTR) of pediatric low-grade, brainstem gliomas may result in a good prognosis. However, unlike pilocytic astrocytoma, diffuse astrocytoma is not easy to perform GTR without any complications. There are some reports regarding GKS for brainstem gliomas, which prove an increase in progression free survival rate. No marked tumor regression is achieved in our case, but tumor growth is well-controlled so far. CONCLUSION GKS after biopsy can be a useful treatment option for pediatric low-grade brainstem gliomas.

We describe the case of a 75-year-old man with pharyngeal hemorrhage caused by a pseudoaneurysm of the lingual artery after accidentally swallowing his dentures. He developed sudden oral and nasal hemorrhage and was transported to a hospital near his residence. The doctors at the hospital diagnosed the case as epistaxis and treated the symptom with nasal packing. However, the bleeding did not stop and his blood pressure decreased. He was then transported to our hospital. We assumed that the bleeding was caused by epistaxis from branches of the internal maxillary artery, and tried to stop bleeding with the endovascular treatment using coils or liquid embolus materials. Angiography showed a pseudoaneurysm of the lingual artery. Coil embolization against the artery was effective in controlling bleeding. Correct diagnosis and appropriate treatments based on the correct diagnosis are essential in this case of swallowed dentures and bleeding of pseudoaneurysm of the lingual artery.

Lumbar spinal fluid drainage is a common procedure for treating hydrocephalus and alleviating vasospasm by egesting blood in the subarachnoid cavity after subarachnoid hemorrhage. Despite being an effective and safe procedure, cerebrospinal fluid overdrainage might result in serious complications. Here we report the case of a 49-year-old man who suffered from tonsillar herniation with subsequent cervicothoracic syringomyelia in the acute phase of subarachnoid hemorrhage due to vertebral artery dissection. About 2 weeks after lumbar drainage was switched from external ventricular drainage initiated on the day of subarachnoid hemorrhage, the recovery from the disturbance of consciousness revealed tetraplegia, and magnetic resonance imaging demonstrated tonsillar herniation and syringomyelia. Removal of the spinal drain and resumption of external ventricular drainage resulted in the restoration of the herniated tonsils to the normal position and the complete disappearance of syringomyelia 11 days later. We should consider that spinal syringomyelia could develop as a complication of lumbar spinal fluid drainage in the acute phase of thick subarachnoid hemorrhage, particularly in the posterior cranial fossa.

Design optimisation technologies are a practical requirement when aiming to obtain optimal product design variable values from an initially given feasible design space, but such technologies also can contribute to the generation of more effective product design alternatives, namely, product design innovations. This paper proposes an effective evaluation method that enables improvement of product design ideas, using characteristic-based hierarchical optimisation strategies applicable to industrial machine products. After related characteristics are decomposed into simpler characteristics, or simpler characteristics are extracted from higher level characteristics, new optimisation strategies are constructed based on clarification of the relationships among all the characteristics. Innovative processes that lead to product design improvements are analysed in detail by examining optimum solutions for various design improvement ideas, using displays of Pareto optimum solution lines or surfaces. The proposed sy...

Antislip control or slip ratio control can help improve the stability of EVs on a low-μ road. However, these control methods cannot control the driving torque. In this paper we propose a driving torque control method for EVs with in-wheel motors. By using this method we can control the driving torque directly. Simulations and experiments are carried out to demonstrate the effectiveness of the proposed method. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(3): 49-58, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21286

Manufacturing that minimises the exhaustion of natural resources, energy used and deleterious environmental impact is increasingly demanded by societies that seek to protect global environments as much as possible. To achieve this, life-cycle design (LCD) is an essential component of product design scenarios; however, LCD approaches have not been well integrated in optimal design methods that support quantitative decision-making. This study presents a method that yields quantitative solutions through optimisation analysis of a basic product design incorporating life-cycle considerations. We consider two types of optimisation approaches that have different aims, namely, (1) to reduce the use of raw materials and energy consumption and (2) to facilitate the reuse of the product or its parts when it reaches the end of its useful life. We also focus on how the optimisation results differ according to the approach used, from the viewpoint of the 3R concept (Reduce, Reuse and Recycling). Our method obtains opti...

Structural optimization methods based on the level set method are a new type of structural optimization method where the outlines of target structures can be implicitly represented using the level set function, and updated by solving the so-called Hamilton–Jacobi equation based on a Eulerian coordinate system. These new methods can allow topological alterations, such as the number of holes, during the optimization process whereas the boundaries of the target structure are clearly defined. However, the re-initialization scheme used when updating the level set function is a critical problem when seeking to obtain appropriately updated outlines of target structures. In this paper, we propose a new structural optimization method based on the level set method using a new geometry-based re-initialization scheme where both the numerical analysis used when solving the equilibrium equations and the updating process of the level set function are performed using the Finite Element Method. The stiffness maximization, eigenfrequency maximization, and eigenfrequency matching problems are considered as optimization problems. Several design examples are presented to confirm the usefulness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.

The SLSV (single-loop-single-vector) method is modified for the reliability-based optimization problem with multiple reliability constraints. The design problem is formulated to minimize the structural volume of frame structure in terms of cross-sectional area of each frame element subjected to the two mode reliability constraints. The two mode reliability criteria consist of the mean compliance and mean eigenfrequency. The limit state functions are formulated as normalized form to achieve numerical stability of the SLSV method, because the functions are directly adopted as constraint conditions. That is a large difference from the conventional double-loop method, where the limit state functions do not appear in the optimization loop. Through numerical examples of 2-D and 3-D frame design problems, higher computational efficiency and sufficient reliability approximation accuracy by the SLSV method are demonstrated in comparison with the conventional double loop method that the mode reliabilities are evaluated by the first order reliability method (FORM) in each optimization step. Additionally, the importance of normalization of the limit state functions in the SLSV method is also demonstrated.

Vibration characteristics such as eigenfrequencies and eigenmodes are crucial factors that determine the dynamic performance of mechanical structures, and high performance structures that function dynamically can be designed by appropriately specifying such vibration characteristics. This paper proposes a structural optimization method for obtaining mechanical structures having specified vibration characteristics, based on the level set method. First, the basic details of a structural optimization method using the level set method, which can be applied to dynamic problems, are briefly discussed. Next, optimization problems that address the maximum eigenfrequencies, and the matching of eigenfrequencies with target values, are formulated. A new optimization algorithm based on the level set method is constructed, where a newly improved geometric re-initialization scheme is used for re-initializing the level set function, based on the zero level set surface. Using the proposed optimization algorithm, both the solving of the eigenvalue problem and the updating of the level set function are performed using the FEM, where unstructured meshes can easily be configured. Finally, several design examples are provided to confirm the usefulness of the proposed structural optimization method.

This paper proposes an optimum system design method that especially considers product lifecycles and aims to help designers make effective decisions during the product design phase. By considering and estimating all lifecycle factors of cost and environmental impact in addition to the product performance, this method facilitates development of optimum design solutions that incorporate requirements pertaining to the product's entire lifecycle. Furthermore, quantitative estimation of lifecycle factors enables the numerical expression of optimum solutions, rather than depending primarily on experiment and designer intuition. To demonstrate the effectiveness of the proposed method, this paper develops an optimum system design method for a milling machine as an example of a machine product designed for long term use. The lifecycle cost and the lifecycle environmental impact are generally expressed as the summation of each value during manufacturing phase, usage phase, disposal phase and recycling phase. In thi...

To achieve truly optimal system reliability, the design of a complex system must address multilevel reliability configuration concerns at the earliest possible design stage, to ensure that appropriate degrees of reliability are allocated to every unit at all levels. However, the current practice of allocating reliability at a single level leads to inferior optimal solutions, particularly in the class of multilevel redundancy allocation problems. Multilevel redundancy allocation optimization problems frequently occur in optimizing the system reliability of multilevel systems. It has been found that a modular scheme of redundancy allocation in multilevel systems not only enhances system reliability but also provides fault tolerance to the optimum design. Therefore, to increase the efficiency, reliability and maintainability of a multilevel reliability system, the design engineer has to shift away from the traditional focus on component redundancy, and deal more effectively with issues pertaining to modular redundancy. This paper proposes a method for optimizing modular redundancy allocation in two types of multilevel reliability configurations, series and series-parallel. A modular design variable is defined to handle modular redundancy in these two types of multilevel redundancy allocation problem. A customized genetic algorithm, namely, a hierarchical genetic algorithm (HGA), is applied to solve the modular redundancy allocation optimization problems, in which the design variables are coded as hierarchical genotypes. These hierarchical genotypes are represented by two nodal genotypes, ordinal and terminal. Using these two genotypes is extremely effective, since this allows representation of all possible modular configurations. The numerical examples solved in this paper demonstrate the efficacy of a customized HGA in optimizing the multilevel system reliability. Additionally, the results obtained in this paper indicate that achieving modular redundancy in series and series-parallel systems provides significant advantages when compared with component redundancy. The demonstrated methodology also indicates that future research may yield significantly better solutions to the technological challenges of designing more fault-tolerant systems that provide improved reliability and lower lifecycle cost.

The shortening of product delivery lead-times can usually be achieved by keeping high-level components in inventory, however in small-volume production systems, maintaining such inventories is often a costly as well as a risky business strategy. If the risk of maintaining unsold inventory can be decreased, even small-volume manufacturers may be able to justify holding more significant quantities of versatile inventory. This paper discusses a component commonality effect to breakthrough the trade-off relationship between inventory levels and delivery lead-times for such small-volume production systems. By using the same component in different products, inventory maintenance costs can be dramatically reduced, but component commonality design problems are inherently complex, since excessive module commonality may lead to lower product performances, and there are trade-off relationships between product performance and cost reductions obtained through component commonality. In this paper, such a design problem...

In optimization problems that aim to minimize sound pressure levels, for simplicity, rather than calculating sound pressure directly, elastic structures have been designed so that fundamental eigen-frequencies rigorously depart from excitation frequencies, or so that radiation efficiency is reduced within target frequency ranges. In this paper, we propose a new topology optimization method for the design of soundproof structures consisting of a poroelastic material and an elastic material, which directly minimizes sound pressure levels inside an acoustic cavity by applying damping material to the system. Biot’s theory is incorporated into the optimization method to deal with the poroelastic material. The elastic material and the air medium surrounding a soundproof structure are equivalently represented in expressions in agreement with Biot’s theory. In this method, a new material interpolation scheme for poroelastic materials based on the density approach is also proposed. Several two-dimensional design problems are presented to demonstrate that the proposed method can provide clear configurations for soundproof structures that reduce sound pressure levels within specified frequency ranges.

This paper proposes an innovative, integrated design method for the design of practical and sophisticated compliant mechanisms. The approach consists of two optimisation methods, topology and shape optimisation, plus a scheme to implement designer input of ideas. In the first step, a designer explores the most fruitful design concepts for mechanisms that achieve the design specifications, by combining compliant mechanisms created by the topology optimisation with additional mechanisms prepared by the designer. In this first step, a support method based on the visualisation of the designer's thinking processes assists the designer in his or her exploration of new ideas and design concepts. In the second step, the shape optimisation yields a detailed optimal shape based on the design concept. The combination of compliant mechanisms with the additional mechanisms enables the creation of devices having increased capability or higher performance than would be possible using a single compliant mechanism designe...

Multilevel redundancy allocation optimization problems (MRAOPs) occur frequently when attempting to maximize the system reliability of a hierarchical system, and almost all complex engineering systems are hierarchical. Despite their practical significance, limited research has been done concerning the solving of simple MRAOPs. These problems are not only NP hard but also involve hierarchical design variables. Genetic algorithms (GAs) have been applied in solving MRAOPs, since they are computationally efficient in solving such problems, unlike exact methods, but their applications has been confined to single-objective formulation of MRAOPs. This paper proposes a multi-objective formulation of MRAOPs and a methodology for solving such problems. In this methodology, a hierarchical GA framework for multi-objective optimization is proposed by introducing hierarchical genotype encoding for design variables. In addition, we implement the proposed approach by integrating the hierarchical genotype encoding scheme with two popular multi-objective genetic algorithms (MOGAs)—the strength Pareto evolutionary genetic algorithm (SPEA2) and the non-dominated sorting genetic algorithm (NSGA-II). In the provided numerical examples, the proposed multi-objective hierarchical approach is applied to solve two hierarchical MRAOPs, a 4- and a 3-level problems. The proposed method is compared with a single-objective optimization method that uses a hierarchical genetic algorithm (HGA), also applied to solve the 3- and 4-level problems. The results show that a multi-objective hierarchical GA (MOHGA) that includes elitism and mechanism for diversity preserving performed better than a single-objective GA that only uses elitism, when solving large-scale MRAOPs. Additionally, the experimental results show that the proposed method with NSGA-II outperformed the proposed method with SPEA2 in finding useful Pareto optimal solution sets.

Electromagnetic waveguides effectively conduct electromagnetic microwaves using resonance phenomena in RF-ranges, and are widely used in high-frequency electronic devices and equipment. The waveguide guiding characteristics related to eigen-frequencies and eigen-modes are critical factors determining the design performances pertaining to the bandwidth of appropriate response frequencies, and high performance electromagnetic waveguides can be obtained by designing cross-sections of waveguides that appropriately control such guiding characteristics at the conceptual design phase. This paper proposes a new application of a topology optimization method for the design of inhomogeneous electromagnetic waveguide cross-sections composed of dielectric material and air, with the resulting configurations performing according to specified guiding characteristics. First, the concept of topology optimization and a way to apply it to electromagnetic wave problems are explained. Next, design requirements for the design of waveguide cross-sections are clarified and corresponding objective functions and the optimization problem are formulated. A new multi-objective function is formulated to reduce grayscales since using a penalization parameter for physical property interpolation is ineffective in electromagnetic problems. The optimization algorithm is constructed based on these formulations, Sequential Linear Programming and the finite element method, where hybrid edge/nodal elements are used. Finally, several design examples of waveguide cross-sections are presented to confirm the usefulness of the proposed method.

In structural designs considering thermal loading, in addition to heat conduction within the structure, the heat convection upon the structure’s surface can significantly influence optimal design configurations. In this paper, we focus on the influence of design-dependent effects upon heat convection and internal heat generation for optimal designs developed using a topology optimization scheme. The method for extracting the structural boundaries for heat convection loads is constructed using a Hat function, and heat convection shape dependencies are taken into account in the heat transfer coefficient using a surrogate model. Several numerical examples are presented to confirm the usefulness of the proposed method.

This paper describes a new design method to optimize thickness distribution of a multilayered structure which is located on the coupling surface between a structure and an acoustic cavity. The design method is based on the concept of the density approach in topology optimization incorporating a transfer matrix for a multilayered structure that includes a poroelastic media layer. The one-dimensional transfer matrix adopted here is an approximate representation addressing vibro-acoustic effects inherent in a multilayered structure, and balances calculation resources and desired accuracy. Applying the transfer matrix representation as boundary conditions on the coupling surface between a structure and an acoustic cavity, the modified equilibrium equation of the vibro-acoustic system is derived which is approximately but efficiently solved by the modal approach. In this study, the problem of minimizing the acoustic pressure within the cavity over the prescribed frequency range is formulated under the volume constraint of the poroelastic media layer. The continuous approximation of thickness distribution is assumed, and the thickness of the poroelastic media layer at each nodal point is chosen as design variables. Numerical results show that an acoustic response is significantly reduced by the optimal thickness distribution having a total weight equal to or less than that in the initial uniform thickness. These demonstrate that the proposed method is effective to design the optimal thickness distribution of a multilayered structure.

Product manufacturing is currently one of the most important activities that people perform, as it directly or indirectly affects the daily life and economic well-being of countless people around the world. It is likely to continue to have a profound effect on world economies by providing a large source of employment and, ideally, by creating products that positively affect the lives of numerous people. For manufacturing to be successful in the long run, a broad range of factors must be taken into account when products are designed and developed. Product manufacturing today requires skilful decision-making in scenarios that are more complex and demanding than ever before, and the use of optimal system technologies has become essential. Readers of System Design Optimization for Product Manufacturing will learn about detailed concepts and practical technologies that enable successful product design and manufacture. These concepts and technologies are based on system optimization methodologies that consider a broad range of mechanical, as well as human, factors. System Design Optimization for Product Manufacturing explains the methodologies behind current and future product manufacture. Its detailed explanations of key concepts are relevant not only for product design and manufacture, but also for other business fields. These core concepts and methodologies can be applied to practically any field where informed decision-making is important, and where a range of often conflicting factors must be carefully weighed and considered. System Design Optimization for Product Manufacturing can be used as a fundamental reference book by both engineers and students in the fields of manufacturing, design engineering, and product development.

This paper focuses on the creative aspects of collaboration and proposes a method for analyzing created ideas to help designers to enhance designers' creativity during collaborative design projects. The proposed method is based on DEA (Data Envelopment Analysis), analyses ideas created by designers to reveal characteristics and overall effectiveness of each idea, interrelationship between ideas and potentially fruitful directions for improvement of created ideas and exploration of new ideas and aims to help designers explore more sophisticated ideas. To enable smooth collaboration when using the proposed analysis method, this paper also proposes a computerized support system. This system is based on a combination of the analysis method proposed here, and the method for visualizing interactive communication processes proposed in our previous work. Analyzing system analyzes created ideas and visualizes the results from the multiple viewpoints, whereas visualizing system records interactive communication processes among designers and visualizes them in an easy-to-understand way.