Quantitative modeling of laser speckle imaging

We have analyzed the image formation and dynamic properties in laser speckle imaging (LSI) both experimentally and with Monte-Carlo simulation. We show for the case of a liquid inclusion that the spatial resolution and the signal itself are both significantly affected by scattering from the turbid environment. Multiple scattering leads to blurring of the dynamic inhomogeneity as detected by LSI. The presence of a non-fluctuating component of scattered light results in the significant increase in the measured image contrast and complicates the estimation of the relaxation time. We present a refined processing scheme that allows a correct estimation of the relaxation time from LSI data.Comment: submitted to Optics Letter

Infrastructure for Detector Research and Development towards the International Linear Collider

The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

El Niño variability off Peru during the last 20,000 years

Here we present a high-resolution marine sediment record from the El Niño region off the coast of Peru spanning the last 20,000 years. Sea surface temperature, photosynthetic pigments, and a lithic proxy for El Niño flood events on the continent are used as paleo–El Niño–Southern Oscillation proxy data. The onset of stronger El Niño activity in Peru started around 17,000 calibrated years before the present, which is later than modeling experiments show but contemporaneous with the Heinrich event 1. Maximum El Niño activity occurred during the early and late Holocene, especially during the second and third millennium B.P. The recurrence period of very strong El Niño events is 60–80 years. El Niño events were weak before and during the beginning of the Younger Dryas, during the middle of the Holocene, and during medieval times. The strength of El Niño flood events during the last millennium has positive and negative relationships to global and Northern Hemisphere temperature reconstructions

Validation of an all-sky imager based nowcasting system for industrial PV plants

Because of the cloud-induced variability of the solar resource, the growing contributions of photovoltaic plants to the overall power generation challenges the stability of electricity grids. To avoid blackouts, administrations started to define maximum negative ramp rates. Storages can be used to reduce the occurring ramps. Their required capacity, durability, and costs can be optimized by nowcasting systems. Nowcasting systems use the input of upward-facing cameras to predict future irradiances. Previously, many nowcasting systems were developed and validated. However, these validations did not consider aggregation effects, which are present in industrial-sized power plants. In this paper, we present the validation of nowcasted global horizontal irradiance (GHI) and direct normal irradiance maps derived from an example system consisting of 4 all-sky cameras (“WobaS-4cam”). The WobaS-4cam system is operational at 2 solar energy research centers and at a commercial 50-MW solar power plant. Besides its validation on 30 days, the working principle is briefly explained. The forecasting deviations are investigated with a focus on temporal and spatial aggregation effects. The validation found that spatial and temporal aggregations significantly improve forecast accuracies: Spatial aggregation reduces the relative root mean square error (GHI) from 30.9% (considering field sizes of 25 m2) to 23.5% (considering a field size of 4 km2) on a day with variable conditions for 1 minute averages and a lead time of 15 minutes. Over 30 days of validation, a relative root mean square error (GHI) of 20.4% for the next 15 minutes is observed at pixel basis (25 m2). Although the deviations of nowcasting systems strongly depend on the validation period and the specific weather conditions, the WobaS-4cam system is considered to be at least state of the art

Musikinstrumentenbau zwischen Tradition und Innovation : Perspektiven aus Theorie und Praxis

Der Tagungsband "Musikinstrumentenbau zwischen Tradition und Innovation" enthält Beiträge der gleichnamigen Tagung (07.–10.03.2024) und der Summerschool Musikinstrumentenbau (02.–14.09.2024). Beide Veranstaltungen fanden am Studiengang Musikinstrumentenbau Markneukirchen der Fakultät Angewandte Kunst Schneeberg der Westsächsischen Hochschule Zwickau statt

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

More humid interglacials in Ecuador during the past 500 kyr linked to latitudinal shifts of the Equatorial Front and the Intertropical Convergence Zone in the eastern tropical Pacific

Studying past changes in the eastern equatorial Pacific Ocean dynamics and their impact on precipitation on land gives us insight into how the Intertropical Convergence Zone (ITCZ) movements and the El Niño‐Southern Oscillation modulate regional and global climate. In this study we present a multiproxy record of terrigenous input from marine sediments collected off the Ecuadorian coast spanning the last 500 kyr. In parallel we estimate sea surface temperatures (SST) derived from alkenone paleothermometry for the sediments off the Ecuadorian coast and complement them with alkenone‐based SST data from the Panama Basin to the north in order to investigate SST gradients across the equatorial front. Near the equator, today's river runoff is tightly linked to SST, reaching its maximum either during the austral summer when the ITCZ migrates southward or during El Niño events. Our multiproxy reconstruction of riverine runoff indicates that interglacial periods experienced more humid conditions than the glacial periods. The north‐south SST gradient is systematically steeper during glacial times, suggesting a mean background climatic state with a vigorous oceanic cold tongue, resembling modern La Niña conditions. This enhanced north‐south SST gradient would also imply a glacial northward shift of the Intertropical Convergence Zone at least in vicinity of the cold tongue: a pattern that has not yet been reproduced in climate models

A NEW CONCEPT FOR LINE-CONCENTRATING CSP COLLECTORS

Line-concentrating systems like the Parabolic Trough or the Linear Fresnel Collector are now ready for deployment and there are several solar thermal power plants planned, under construction or connected to the grid using these types of concentrators. Yet, both concepts comprise some disadvantages and there is little chance for cost-reduction and performance-enhancement when the concentrators shape is not altered. In this paper, a different approach is presented, characterized by the collector’s focal line interfering with the center of mass. This is achieved by the segmentation of the mirror surface, which enables the implementation of a Fixed Focus Parabolic Trough. The structure is integrated into the reflective area by what the wind loads are considerably reduced. Expensive and frail key-components like flexible tube connectors can be omitted. The length of the reflected light rays is considerably shorter compared to other collectors with the same aperture, thus promising an excellent optical efficiency