Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentia...Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions.展开更多
For centrifugal compressors used in automotive turbochargers, the extension of the surge margin is demanded because of lower engine speed. In order to estimate the surge line exactly, it is required to acquire the com...For centrifugal compressors used in automotive turbochargers, the extension of the surge margin is demanded because of lower engine speed. In order to estimate the surge line exactly, it is required to acquire the compressor characteristics at small or negative flow rate. In this paper, measurement and numerical simulation of the characteristics at small or negative flow rate are carried out. In the measurement, an experimental facility with a valve immediately downstream of the compressor is used to suppress the surge. In the numerical work, a new boundary condition that specifies mass flow rate at the outlet boundary is used to simulate the characteristics around the zero flow rate region. Furthermore, flow field analyses at small or negative flow rate are performed with the numerical results. The separated and re-circulated flow fields are investigated by visualization to identify the origin of losses.展开更多
Acute lymphoblastic leukemia/lymphoma is a highly aggressive neoplasm of precursor lymphoid (blast) cells. There are 2 main subtypes based on lymphoid lineage;B lymphoblastic leukemia/lymphoma (B-ALL/LBL) and T lympho...Acute lymphoblastic leukemia/lymphoma is a highly aggressive neoplasm of precursor lymphoid (blast) cells. There are 2 main subtypes based on lymphoid lineage;B lymphoblastic leukemia/lymphoma (B-ALL/LBL) and T lymphoblastic leukemia/lymphoma (T-ALL/LBL). B-ALL/LBL commonly presents with fever, fatigue, bone or joint pain, bleeding or anorexia (signs of bone marrow infiltration), lymphadenopathy, hepatosplenomegaly, involvement of skin, soft tissue and testes, with a predilection for the central nervous system. Immature cell markers, such as CD34 and TdT, can help to differentiate lymphoblasts from Burkitt lymphoma which, is considered a mature high-grade B cell lymphoma that mimics lymphoblastic lymphoma/leukemia. Unfavorable prognostic factors include: infancy and adult age of diagnosis, high white blood cell count, slow response to initial therapy, central nervous system involvement at the time of diagnosis and Minimal residual disease after therapy. We present a case report of a 4 months old infant seen at a Tertiary Hospital with a rare presentation of CD34 Negative B-lymphoblastic leukemia/lymphoma presenting as cutaneous lesions in infancy.展开更多
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant No.2022R1I1A1A01069442)the 2024 Hongik University Research Fund。
文摘Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions.
文摘For centrifugal compressors used in automotive turbochargers, the extension of the surge margin is demanded because of lower engine speed. In order to estimate the surge line exactly, it is required to acquire the compressor characteristics at small or negative flow rate. In this paper, measurement and numerical simulation of the characteristics at small or negative flow rate are carried out. In the measurement, an experimental facility with a valve immediately downstream of the compressor is used to suppress the surge. In the numerical work, a new boundary condition that specifies mass flow rate at the outlet boundary is used to simulate the characteristics around the zero flow rate region. Furthermore, flow field analyses at small or negative flow rate are performed with the numerical results. The separated and re-circulated flow fields are investigated by visualization to identify the origin of losses.
文摘Acute lymphoblastic leukemia/lymphoma is a highly aggressive neoplasm of precursor lymphoid (blast) cells. There are 2 main subtypes based on lymphoid lineage;B lymphoblastic leukemia/lymphoma (B-ALL/LBL) and T lymphoblastic leukemia/lymphoma (T-ALL/LBL). B-ALL/LBL commonly presents with fever, fatigue, bone or joint pain, bleeding or anorexia (signs of bone marrow infiltration), lymphadenopathy, hepatosplenomegaly, involvement of skin, soft tissue and testes, with a predilection for the central nervous system. Immature cell markers, such as CD34 and TdT, can help to differentiate lymphoblasts from Burkitt lymphoma which, is considered a mature high-grade B cell lymphoma that mimics lymphoblastic lymphoma/leukemia. Unfavorable prognostic factors include: infancy and adult age of diagnosis, high white blood cell count, slow response to initial therapy, central nervous system involvement at the time of diagnosis and Minimal residual disease after therapy. We present a case report of a 4 months old infant seen at a Tertiary Hospital with a rare presentation of CD34 Negative B-lymphoblastic leukemia/lymphoma presenting as cutaneous lesions in infancy.
