وأيد هذا العمل من قبل وزارة العلوم الهندسة الميكانيكية و، جامعة إلينوي في أوربانا شامبين، كجزء من حزمة البدء ليوناردو P. تشامورو.

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الكتاب تعلن أنه ليس لديهم مصلحة مالية المتنافسة.

<html> 3D-PTV لديها امكانات كبيرة لكشف الفيزياء معقدة من مجموعة متنوعة من التدفقات المضطربة مثل حركات مضطربة على نطاق واسع في الغلاف الجوي السفلي 25، توزيع الهواء في الأماكن المغلقة 26، أو التدفقات نابض في طوبولوجيا الأبهر 28 ضمن أشياء أخرى كثيرة. ومع ذلك، ف...

التدفقات طائرة مضطربة موجودة في كل مكان في التطبيقات الهندسية. وصف مفصل لهذه التدفقات أمر بالغ الأهمية في طائفة واسعة من المشاكل العملية التي تمتد من أنظمة تصريف البيئي على نطاق واسع لأجهزة الصغيرة الحجم الإلكترونية. لما له من تأثير على عدد من تطبيقات واسعة، وقد تم دراسة التدفقات طائرة في عمق 1-4. العديد من التقنيات التجريبية، بما في ذلك anemometry شبان 4-8، ليزر دوبلر السرعة بواسطة (LDV) 4، 9 - وقد استخدمت 16، لوصف تدفق طائرة في مجموعة واسعة من أرقام رينولدز والحدود - 12، والجسيمات صورة السرعة بواسطة (التعريف الشخصية) 12 الظروف. في الآونة الأخيرة، بذلت عدد قليل من الدراسات باستخدام 3D-PTV لدراسة / واجهة مضطربة غير مضطربة من تدفقات طائرة 17 و 18. 3D-PTV هي تقنية مناسبة خاصة لوصف فاي المضطرب معقدةelds من منظور مختلف. وهو يتيح للإعمار مسارات الجسيمات داخل وحدة تخزين في إطار لاغرانج المرجعية باستخدام متعددة بغية الاستريوسكوبية. وقد أدخلت هذه التقنية لأول مرة من قبل تشانغ 19 والتي طورها RACCA وديوي 20. منذ ذلك الحين، تم إجراء العديد من التحسينات على خوارزمية 3D-PTV والإعداد التجريبية 21-24. مع هذه الإنجازات والأعمال السابقة، وقد استخدم النظام بنجاح لدراسة مختلف الظواهر السوائل مثل حركة السوائل على نطاق واسع في مجال من 4 م × 2 م × 2 م 25، في الأماكن المغلقة مجال تدفق الهواء 26، يتدفق نابض 27 و الدم الأبهري تدفق 28 . مبدأ عمل قياس 3D-PTV يتكون من نظام الحصول على البيانات انشاء وتسجيل / التجهيز المسبق والمعايرة والمراسلات 3D، وتتبع الزمني ومرحلة ما بعد المعالجة. معايرة دقيقة يسمح لكشف دقيق للموقف الجسيماتالصورة. المراسلات من الجزيئات المكتشفة في أكثر من ثلاث وجهات نظر الصورة تسمح لإعادة بناء موقف الجسيمات 3D على أساس الهندسة epipolar. والربط من إطارات الصور متتالية يؤدي إلى تتبع الزمني الذي يحدد مسارات الجسيمات ق (ر). تعظيم الاستفادة من نظام 3D-PTV ضروري لتحقيق أقصى قدر من احتمال التتبع متعددة الجسيمات. الخطوة الأولى من الأمثل هو في الحصول على نظام الحصول على البيانات المناسبة بما في ذلك كاميرات عالية السرعة، مصدر الإضاءة وخصائص الجسيمات البذر. القرار الكاميرا مع حجم وحدة التخزين الاستجواب يحدد حجم البكسل، وبالتالي فإن المطلوب منبذرة حجم الجسيمات، التي ينبغي أن تكون أكبر من بكسل واحد. وتقدر centroids الجسيمات رصدها بدقة بكسل الفرعي عن طريق أخذ متوسط ​​موضع بكسل الجسيمات مرجحة سطوع 21. معدل الإطار الكاميرا وASSOCIAT عن كثبإد مع عدد رينولدز والقدرة على الربط بين الجزيئات المكتشفة. ويسمح معدل الإطار العالي لتسوية التدفقات أسرع أو عدد أكبر من جزيئات منذ تتبع يصبح أكثر صعوبة عندما يتجاوز يعني تشريد بين الصور فصل نفسه من الجزيئات. سرعة مصراع الكاميرا، والفتحة والحساسية هي ثلاثة عوامل للنظر في التقاط الصور. يجب أن تكون سرعة مصراع بسرعة كافية للحد من عدم وضوح حول الجسيمات، مما يقلل من حالة عدم اليقين من موقف الجسيمات النقطه الوسطى. ينبغي تعديل فتحة الكاميرا إلى عمق الميدان من حجم الاستجواب للحد من احتمال الكشف عن جزيئات خارج وحدة التخزين. منذ يتم إصلاح الحساسية القصوى من الكاميرا، كما يزيد معدل الإطار، وعلى ضوء اللازمة لإلقاء الضوء على جزيئات يجب زيادة وفقا لذلك. على عكس التعريف الشخصية، لا تتطلب إعدادات البصرية المعقدة والليزر عالية الطاقة بدقة في 3D-PTV، طالما كان مصدر الضوء بما فيه الكفاية الموسيقيمحله من الجسيمات التتبع إلى الكاميرا. مستمرة LED أو مصابيح الهالوجين هي خيارات جيدة فعالة من حيث التكلفة التي تتجاوز الحاجة التزامن 21. في 3D-PTV، مثل غيرها من التقنيات لقياس التدفق الضوئي، يفترض سرعة التتبع الجسيمات ليكون المحلية لحظية سرعة السائل 29. ومع ذلك، هذه ليست سوى حالة لاستشفاف مثالية من قطر لاغية والجمود. وينبغي أن تكون الجسيمات التتبع كبيرة بما يكفي ليتم القبض بواسطة كاميرا. الاخلاص من الجسيمات المتناهية يمكن تحديدها من قبل ستوكس عدد S ر، أي نسبة من حجم الوقت الاسترخاء من الجسيمات والنطاق الزمني لهياكل المضطربة من الفائدة. بشكل عام، يجب S ر يكون أصغر بكثير من 1. لS ر ≤0.1 أخطاء تتبع تدفق هي أقل من 1٪ 30. في العمق يمكن العثور على مناقشة في مي وآخرون 29 - 31 </sup&gt;. وأوصى حجم الجسيمات لتجربة 3D-PTV يختلف تبعا لمصدر الضوء وحساسية الكاميرا. مع الهالوجين أو مصابيح LED كمصدر إضاءة، وتستخدم الجزيئات الكبيرة نسبيا (على سبيل المثال 50-200 ميكرون) 32، في حين أن جسيمات أصغر (على سبيل المثال 1-50 ميكرون) 33، 34 يمكن استخدامها مع ليزر عالية الطاقة (على سبيل المثال 80-100 واط ليزر CW). الجسيمات مع انعكاسية عالية للضوء طول موجي معين، مثل الفضة المطلية تحت ضوء الهالوجين، يمكن أن تزيد بصماتها إلى صورة. كثافة البذر هي المعلمة هامة أخرى لقياس 3D-PTV ناجحة. قليل من جزيئات تؤدي إلى انخفاض عدد مسارات، في حين أن عدد كبير من الجزيئات تسبب الغموض في إنشاء المراسلات وتتبع. وتشمل النقاط الغامضة في إنشاء المراسلات الجسيمات المتداخلة وكشف المرشحين متعددة على طول الخط epipolar محددة. في عملية تتبع، والغموض بسبب seedin عالية<html> ووقع ز كثافة بسبب قصيرة نسبيا فصل نفسه من الجزيئات. الخطوة الثانية هي الإعدادات المثلى في تسجيل / التجهيز المسبق لتعزيز جودة الصورة. إعدادات التصوير، مثل زيادة ومستوى الأسود (G &amp; B)، وتلعب دورا هاما في تحسين جودة الصورة. يحدد مستوى السواد مستوى السطوع في أحلك جزء من الصورة، في حين كسب تضخيم سطوع الصورة. اختلافات طفيفة في مستويات G &amp; B يمكن أن تؤثر بدرجة كبيرة على احتمال التتبع. في الواقع، وارتفاع G &amp; B قد الإفراط في سطع صورة وتضر في نهاية المطاف من مستشعر الكاميرا. لتوضيح ذلك، يتم فحص تأثير G &amp; B المستويات على إعادة تدفق أيضا في هذه المقالة. في الخطوة ما قبل المعالجة، يتم تصفيتها الصور مع فلتر تمريرة عالية للتأكيد على الضوء المبعثر من جزيئات. يتم ضبط حجم بكسل ومقياس الرمادية لتحقيق أقصى قدر من كشف الجسيمات داخل حجم الاستجواب. ر &quot;&gt; الخطوة الثالثة من الأمثل هو معايرة دقيقة من التصوير ثلاثي الأبعاد، والتي تقوم على الهندسة epipolar، المعلمات الكاميرا (البعد البؤري، وأشر حيث المبدأ، ومعاملات تشويه)، والتغيرات معامل الانكسار. وهذه العملية ضرورية لتقليل 3D الخطأ إعادة بناء نقطة الهدف الإيمانية. هندسة Epipolar يستخدم المسافات النسبية (بين الكاميرا وحجم الاستجواب) وزاوية مائلة من صورة الهدف. التغييرات مؤشر الانكسار على طول عرض الكاميرا من خلال حجم الاستجواب يمكن أن تؤخذ بعين الاعتبار على أساس إجراء القداس وآخرون. 21. في هذه التجربة، ويستخدم بنية تشبه درج 3D مع نقطة الهدف موزعة بانتظام هدفا. في تجربة 3D-PTV، على الرغم من أن هناك حاجة إلى اثنين فقط من الصور لتحديد موقف الجسيمات 3D، وتستخدم عادة أكثر الكاميرات للحد من الغموض 21. بديلا للالاجهزة غالية الثمن مع العديد من كاميرات عالية السرعة هو السادسالخائن مصريات، التي اقترحها هوير وآخرون. (35) لاستخدام 3D-PTV وتطبيقها مؤخرا Gulean وآخرون. (28) لالتطبيقات الطبية الحيوية. يتكون الخائن ضوء مرآة على شكل هرم (المرآة الأولية الآن فصاعدا) وأربعة المرايا قابل للتعديل (الآن فصاعدا مرآة الثانوية). في هذا العمل، واستخدمت الخائن أربعة عرض وكاميرا واحدة لتقليد التصوير مجسمة من أربع كاميرات. ويستخدم نظام لتوصيف مجال تدفق وسيط لطائرة الأنابيب التي يبلغ قطرها، د ح = 1 سم وإعادة ≈ 7000 من لاغرانج وإطارات عالم رياضيات ألماني في جميع أنحاء 14،5-18،5 أقطار المصب من أصل طائرة.

<table border="0" cellpadding="0" cellspacing="0" width="749">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">ImageOps</td>
			<td style="width:119px;">CAMMC4082</td>
			<td style="width:407px;">High-speed camera</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">ImageOps</td>
			<td style="width:119px;">FBD-4XCXP6</td>
			<td>Frame Grabber</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:223px;">Potters Industries LLC</td>
			<td style="width:119px;">AG-SL150-30-TRD</td>
			<td>Seeding Paritcles</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:223px;">Upstate Technical Equipment CO.,INC</td>
			<td style="width:119px;">MISNOR-STP-6-S-CL</td>
			<td>Camera appliation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Photrack AG</td>
			<td style="width:119px;"></td>
			<td>Customized part and necessary if performing 3D-PTV with one camera</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">General Electrics&#160;</td>
			<td style="width:119px;">23719</td>
			<td>Light source</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">OpenPTV(http://www.openptv.net)</td>
			<td style="width:119px;"></td>
			<td>Open source particle tracking software (Note: available as a service for anyone who wants to use it without all the installation mess or computer power availability problems).</td>
		</tr>
	</tbody>
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three-dimensional particle tracking velocimetry for turbulence applications: case of a jet flow

3D-PTV هو الكمية التقنية لقياس التدفق والتي تهدف لتتبع مسارات لاغرانج من مجموعة من الجسيمات في الأبعاد الثلاثة باستخدام تسجيل مجسمة من تسلسل الصور. موصوفة الأساسية مكونات وخصائص والقيود ونصائح التحسين من طوبولوجيا 3D-PTV تتكون من كاميرا عالية السرعة مع الخائن أربعة الرأي ومناقشتها في هذه المقالة. يتم تطبيق هذه التقنية إلى الميدان وسيط تدفق (5 &lt;س / د &lt;25) من طائرة دائرية في إعادة ≈ 7000. وتقدر ميزات تدفق لاغرانج وكميات الاضطراب في إطار عالم رياضيات الماني نحو عشرة أقطار المصب من أصل طائرة وعلى مسافات مختلفة شعاعي من صميم طائرة. وتشمل خصائص لاغرانج مسار والسرعة وتسريع الجسيمات مختارة، فضلا عن انحناء مسار التدفق، والتي يتم الحصول عليها من المعادلة Frenet-Serret. تقدير مجالات السرعة والاضطراب 3D حول محور الأساسية طائرة في الطائرة عبر يقع في عشرةبأقطار المصب من الطائرة تتم مقارنة مع الأدب، ويتم الحصول على الطيف سلطة واسعة النطاق الاقتراحات streamwise سرعة على مسافات مختلفة شعاعي من صميم طائرة.

وأظهرت صورة والتخطيطي من الإعداد في أرقام 1 و 2. هدف المعايرة، تعكس علامات إيمانية على عرض الخائن و 3D إعادة الإعمار معايرة موضحة في الشكل (3). وRMS من أهداف المعايرة المعترف بها هي 7.3 ميكرون، 5.7 ميكرون و 141.7 مي...

Watch this Scientific Journal Video about Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow at JoVE.com

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

ووصف ثلاثي الأبعاد تتبع الجسيمات السرعة بواسطة (3D-PTV) نظام يقوم على كاميرا عالية السرعة مع الخائن أربعة الرأي هنا. يتم تطبيق هذه التقنية لتدفق طائرة من أنبوب دائري في محيط عشرة أقطار المصب في عدد رينولدز إعادة ≈ 7000.

ثلاثي الأبعاد السرعة بواسطة الجسيمات تتبع للتطبيقات الاضطراب: حالة من تدفق جت

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

three-dimensional-particle-tracking-velocimetry-for-turbulence

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12.1K Views.  University of Illinois at Urbana-Champaign.  ووصف ثلاثي الأبعاد تتبع الجسيمات السرعة بواسطة (3D-PTV) نظام يقوم على كاميرا عالية السرعة مع الخائن أربعة الرأي هنا. يتم تطبيق هذه التقنية لتدفق طائرة من أنبوب دائري في محيط عشرة أقطار المصب في عدد رينولدز إعادة ≈ 7000. 

Video: Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

Echo Particle Image Velocimetry

The transport of mass, momentum, and energy in fluid flows is ultimately determined by spatiotemporal distributions of the fluid velocity field.1 Consequently, a prerequisite for understanding, predicting, and controlling fluid flows is the capability to measure the velocity field with adequate spatial and temporal resolution.2 For velocity measurements in optically opaque fluids or through optically opaque geometries, echo particle image velocimetry (EPIV) is an attractive diagnostic technique to generate "instantaneous" two-dimensional fields of velocity.3,4,5,6 In this paper, the operating protocol for an EPIV system built by integrating a commercial medical ultrasound machine7 with a PC running commercial particle image velocimetry (PIV) software8 is described, and validation measurements in Hagen-Poiseuille (i.e., laminar pipe) flow are reported.
For the EPIV measurements, a phased array probe connected to the medical ultrasound machine is used to generate a two-dimensional ultrasound image by pulsing the piezoelectric probe elements at different times. Each probe element transmits an ultrasound pulse into the fluid, and tracer particles in the fluid (either naturally occurring or seeded) reflect ultrasound echoes back to the probe where they are recorded. The amplitude of the reflected ultrasound waves and their time delay relative to transmission are used to create what is known as B-mode (brightness mode) two-dimensional ultrasound images. Specifically, the time delay is used to determine the position of the scatterer in the fluid and the amplitude is used to assign intensity to the scatterer. The time required to obtain a single B-mode image, t, is determined by the time it take to pulse all the elements of the phased array probe. For acquiring multiple B-mode images, the frame rate of the system in frames per second (fps) = 1/&delta;t. (See 9 for a review of ultrasound imaging.)
For a typical EPIV experiment, the frame rate is between 20-60 fps, depending on flow conditions, and 100-1000 B-mode images of the spatial distribution of the tracer particles in the flow are acquired. Once acquired, the B-mode ultrasound images are transmitted via an ethernet connection to the PC running the PIV commercial software. Using the PIV software, tracer particle displacement fields, D(x,y)[pixels], (where x and y denote horizontal and vertical spatial position in the ultrasound image, respectively) are acquired by applying cross correlation algorithms to successive ultrasound B-mode images.10 The velocity fields, u(x,y)[m/s], are determined from the displacements fields, knowing the time step between image pairs, &Delta;T[s], and the image magnification, M[meter/pixel], i.e., u(x,y) = MD(x,y)/&Delta;T. The time step between images &Delta;T = 1/fps + D(x,y)/B, where B[pixels/s] is the time it takes for the ultrasound probe to sweep across the image width. In the present study, M = 77[&mu;m/pixel], fps = 49.5[1/s], and B = 25,047[pixels/s]. Once acquired, the velocity fields can be analyzed to compute flow quantities of interest.

An echo particle image velocimetry (EPIV) system capable of acquiring two-dimensional fields of velocity in optically opaque fluids or through optically opaque geometries is described, and validation measurements in pipe flow are reported.

صدى الجسيمات Velocimetry صورة

The transport of mass, momentum, and energy in fluid flows is ultimately determined by spatiotemporal distributions of the fluid velocity field.1 ...

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

عملية صنع المجهرية ثلاثي الأبعاد باستخدام تبخير مكون قرباني

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

High-speed Particle Image Velocimetry Near Surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

عالي السرعة الجسيمات Velocimetry صورة قرب السطوح

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.

تصور عالية السرعة السائل جيت الانحشار على السطح المتحرك

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

توصيف النانوية الحجم التوزيع باستخدام مطيافية رامان مع متعددة الجسيمات الطاقة الصوتية الحبس نموذج

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Development of an Experimental Setup for the Measurement of the Coefficient of Restitution under Vacuum Conditions

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their behavior for single stages of a process or even an entire process. For the simulation with occurring particle-particle and particle-wall contacts, the value of the coefficient of restitution is required. It can be determined experimentally. The coefficient of restitution depends on several parameters like the impact velocity. Especially for fine particles the impact velocity depends on the air pressure and under atmospheric pressure high impact velocities cannot be reached. For this, a new experimental setup for free-fall tests under vacuum conditions is developed. The coefficient of restitution is determined with the impact and rebound velocity which are detected by a high-speed camera. To not hinder the view, the vacuum chamber is made of glass. Also a new release mechanism to drop one single particle under vacuum conditions is constructed. Due to that, all properties of the particle can be characterized beforehand.

The coefficient of restitution is a parameter that describes the loss of kinetic energy during collision. Here, a free-fall setup under vacuum conditions is developed to be able to determine the coefficient of restitution parameter for particles in micrometer range with high impact velocities.

وضع الإعداد التجريبية لقياس معامل الرد تحت ظروف الفراغ

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

أساليب لقياس التوجيه ودوران معدل الجسيمات في الاضطرابات 3D-طباعة

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

باستخدام السنكروترون الإشعاع مجهري المعنية بالتحقيق في نطاق متعدد الحزم الإلكترونية الدقيقة ثلاثي الأبعاد

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. When visualization is lost, the medical device can cause trauma to critical tissue structures. Here, a method to track the needle tip during ultrasound image-guided procedures is presented. This method involves the use of a fiber-optic ultrasound receiver that is affixed within the cannula of a medical needle to communicate ultrasonically with the external ultrasound probe. This custom probe comprises a central transducer element array and side element arrays. In addition to conventional two-dimensional (2D) B-mode ultrasound imaging provided by the central array, three-dimensional (3D) needle tip tracking is provided by the side arrays. For B-mode ultrasound imaging, a standard transmit-receive sequence with electronic beamforming is performed. For ultrasonic tracking, Golay-coded ultrasound transmissions from the 4 side arrays are received by the hydrophone sensor, and subsequently the received signals are decoded to identify the needle tip&#39;s spatial location with respect to the ultrasound imaging probe. As a preliminary validation of this method, insertions of the needle/hydrophone pair were performed in clinically realistic contexts. This novel ultrasound imaging/tracking method is compatible with current clinical workflow, and it provides reliable device tracking during in-plane and out-of-plane needle insertions.

Accurate and efficient visualization of invasive medical devices is extremely important in many ultrasound-guided minimally invasive procedures. Here, a method for localizing the spatial position of a needle tip relative to the ultrasound imaging probe is presented.

إبرة الموجات فوق الصوتية ثلاثية الأبعاد نصيحة تتبع مع جهاز استقبال الموجات فوق الصوتية الألياف البصرية

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

قياس واحد من الاضطراب والجسيمات الكينماتيكا التدفق تقنيات التصوير باستخدام

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...