njit-etd2003-081 - New Jersey Institute of Technology

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175 All of the WT time-frequency representations shown in Figures 5.12 - 5.16 are somewhat similar. A band of cones of influence corresponding to each minimum and maximum points on the HR IIBI signal at the frequency of respiration (16 bpm, 0.266667 Hz) appears in each wavelet transform representation. However, the power intensity of the band is not as high as the similar band shown in the normal subject case investigated in section 5.2.2. Another band of cones of influence in the very low frequency range (0.01 — 0.15 Hz) also exists with higher energy and in longer time (from 10 seconds to 120 seconds, to 180 seconds, to 250 seconds). Among the wavelets, the Monet wavelet provides the best representation in terms of time, frequency resolution and meaningful details. The band of the cones of influence at 0.266667 Hz is modulated slightly indicating that the respiration is not a stationary signal. 5.2.4 Best Time-Frequency Representations for HRV Study In this part of the study, one chooses the best of four time-frequency representations and a wavelet distribution to analyze the HRV signal. The criterion for the best selection of distribution includes: 1. Sharp frequency band representation without smearing to the next frequency band. 2. Little or no interference (cross-term). 3. High amplitude representation that corresponds well with amplitude of original signal. These criteria are used basically in visual inspection of the 3D and contour timefrequency plots. However, a more scientifically accepting method is needed that will be presented in the next section.
176 5.2.5 Best Wavelet Selection for HRV Time-frequency Representation Wavelet representations show more details than the classical time frequency representation such as the Cohen's class distributions. Among the different wavelets used in the analysis, the Monet wavelet seems to be the right choice of wavelet for analyzing the actual physiological signals of BP, respiration and heart rate variability signal (derived from the ECG) when visual inspection was performed. Here the author proposes using the cross-correlation to help make this decision. The technique of cross-correlation was used to compare the power spectrum derived wavelet coefficients (power) versus frequency obtained from the 3D scalogram representations of the HRV 11131 signals of COPD subjects to the power spectrum of the same signal using Fourier analysis. The Fourier analysis power spectrum was used because Fourier analysis provided the perfect representation of the signal power in the frequency domain. Any wavelet representation considered as best representation must have the highest cross-correlation index value when comparing the wavelet power spectrum with the Fourier power spectrum. The cross-correlation between two signals measures the way the signals change with respect to one another. In other words, if f(x) always increases and decreases as g(x) increases and decreases, then f(x) and g(x) are positively correlated. The correlation of two continuous functions f(x) and g(x), denoted as f (x) • g(x), is defined by the following equation [25]: where * is the complex conjugate. For this study, the power spectrum signals were not complex. Therefore, to calculate the cross-correlation, the function g(x) is shifted, by
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Copyright Warning & Restrictions Th
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ABSTRACT TIME-FREQUENCY INVESTIGATI
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TIME-FREQUENCY INVESTIGATION OF HEA
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APPROVAL PAGE TIME-FREQUENCY INVEST
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BIOGRAPHICAL SKETCH (Continued) D.A
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ACKNOWLEDGMENT The author wishes to
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TABLE OF CONTENTS Chapter Page 1 IN
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TABLE OF CONTENTS (Continued) Chapt
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LIST OF FIGURES Figure Page 2.1 The
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LIST OF FIGURES (Continued) Figure
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LIST OF FIGURES (Continued) Figure
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ABBREVIATIONS A ABP Arterial Blood
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ABBREVIATIONS (Continued) P PID Pro
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2 mortality and sudden death. [2] B
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4 1) Patients with severe pulmonary
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6 examined for determining the inte
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8 identified using principal compon
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1 0 1. Present the application of t
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12 1.3 Outline of the Dissertation
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CHAPTER 2 PHYSIOLOGY BACKGROUND Bio
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16 Figure 2.2 The systemic and pulm
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18 illustrated in Figure 2.3. The i
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20 2.2 Blood Pressure The force tha
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22 2.4 The Nervous System Human beh
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24 The sympathetic nerve fibers lea
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26 Without these sympathetic and pa
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28 center in the medulla, which con
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30 Figure 2.6 Autonomic innervation
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32 average heart rate was measured
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34 However, they do note that there
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Figure 2.9 The placement of the pos
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38 female. While more men suffer fr
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40 Stage II: Moderate COPD - Worsen
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CHAPTER 3 ENGINEERING BACKGROUND Th
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44 Two common types of time-frequen
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46 STFT: Short-Time Fourier Transfo
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48 3.3 The Analytic Signal and Inst
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50 The advantage of using equation
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52 3.5 Covariance and Invariance Th
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where H(f), S(f) are Fourier transf
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56 Another shortcoming of the spect
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58 should take the kernel of the WD
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60 called the cross Wigner distribu
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62 3.6.3 The Choi-Williams (Exponen
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64 Figure 3.3 Performance of the Ch
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66 [-Ω,Ω ], then its STFT will be
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68 This condition forces that the w
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70 where c is a constant. Thus, the
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Figure 3.5 The time-frequency plane
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74 The measure dadb used in the tra
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76 and the wavelet transform repres
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78 Figure 3.6 Figure depicting the
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80 The final step to obtain the pow
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82 It should be noted that if the w
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84 The normal respiration rate can
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Figure 3.12 Power spectrum of BP II
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RR similar manner to give: When com
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90 when there is significant correl
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92 3.12 Partial Coherence Analysis
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94 after removal of the effects of
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96 The bulk of the theory and appli
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98 technique is measurement time. T
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100 usually attainable. The key poi
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102 variability exists in the propa
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104 eXogenous input (ARX) was used
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106 The baroreflex, an autonomic re
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108 the principal components are no
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110 The mathematical solution for t
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112 3.15 Cluster Analysis The term
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114 formed) one can read off the cr
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116 3.15.5 Squared Euclidian Distan
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118 Alternatively, one may use the
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120 Sneath and Sokal used the abbre
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122 may seem a bit confusing at fir
Page 153 and 154: CHAPTER 4 METHODS The purpose of th
Page 155 and 156: 126 4.1.2.1 Autonomic Testing. HR V
Page 157 and 158: 128 of heart rate, blood pressure,
Page 159 and 160: 130 The patients who underwent LVRS
Page 161 and 162: 132 panel of the Correct.vi. It was
Page 163 and 164: 134 4.2.3 Power Spectrum Analysis o
Page 165 and 166: 136 weighted-average value of the c
Page 167 and 168: 138 For each given scale a within t
Page 169 and 170: 140 frequency F to the wavelet func
Page 171 and 172: 142 4.2.8 System Identification Ana
Page 173 and 174: 144 In this study a simpler approac
Page 175 and 176: 146 Table 4.2 Parameters That Make
Page 177 and 178: 148 4.2.11 Cluster Analysis The sam
Page 179 and 180: 150 viewing the time series of sequ
Page 181 and 182: Figure 5.2 BPV analysis of a COPD s
Page 183 and 184: Figure 5.3 HRV analysis of a normal
Page 185 and 186: Figure 5.4.1 Comparison of the HRV
Page 187 and 188: 158 5.2 Time Frequency Analysis One
Page 189 and 190: Figure 5.5 Test signal with 3 sine
Page 191 and 192: 162 Figure 5.6 (c) CWD of a signal
Page 193 and 194: 164 Figure 5.7 (c) WT (dB4 wavelet)
Page 195 and 196: 166 HRV more information about HRV
Page 197 and 198: 168 Figure 5.9 (c) CWD plots of a n
Page 199 and 200: Figure 5.10 CWT (Morlet) HRV plot o
Page 201 and 202: 172 The following figures show the
Page 203: 174 Figure 5.15 CWT (Mexican Hat) H
Page 207 and 208: 178 Table 5.1 Correlation Indices o
Page 209 and 210: 180 5.2.6 Vagal Tone and Sympathova
Page 211 and 212: 182 These figures basically show th
Page 213 and 214: 184 Figure 5.20 Sympathetic and par
Page 217 and 218: 188 5.2.7 Time-Frequency Analysis (
Page 219 and 220: 190 Figure 5.29 3D and contour plot
Page 221 and 222: 192 Figure 5.33 3D and contour plot
Page 229 and 230: Figure 5.44 Plot of raw respiration
Page 231 and 232: Figure 5.46 The LF partial coherenc
Page 233 and 234: Figure 5.48 HF partial coherence pl
Page 235 and 236: Table 5.2 Cross-Spectral Analysis o
Page 237 and 238: Table 5.3 Cross-Spectral Analysis o
Page 239 and 240: Figure 5.50 HF coherence of COPD (1
Page 241 and 242: 212 For better presentation of the
Page 243 and 244: Figure 5.53 Coherence and partial c
Page 245 and 246: 216 2. Interpretation of the transf
Page 247 and 248: 218 covariances of the parameters,
Page 249 and 250: 220 deviations are interpreted as A
Page 251 and 252: 222 Figure 5.58 Bode plot of the HR
Page 253 and 254: 224 In this section a simple model
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226 The data for all 47 COPD subjec
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228 Figure 5.60 Normal and COPD cla
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230 Figure 5.61 Normal and COPD cla
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232 Figure 5.62 Normal classificati
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234 5.7 Cluster Analysis The purpos
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236 Figure 5.64 Severity classifica
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238 both the normal and COPD subjec
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240 In summary, COPD subjects had h
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APPENDIX A EXERCISE PHYSIOLOGY A.1
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244 A.3 Figure Out Your Target Hear
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APPENDIX B ANALYSIS PROGRAM LISTING
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248 4) Click on file, close to exit
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250 • TN 11
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252 B.1.2 Partial Coherence Between
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254
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256 Block Diagram !rime of record K
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258
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260 B.2.2 Time — Frequency Analys
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262 This program provides the STFT
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264 G(:j+1)=G(:,j+1)/(2*sum(G(:j+1)
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266 T=(length(Signa)/sample)/(Times
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268 subplot(3, 1,3), plot(T,E); xla
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270 4. The program creates five out
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272 B.2.3.4 Program to Generate Sym
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274 ylabel('frequency'); title('Ins
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276 The program will run and output
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278 axis([0 1 0 2]); grid on; xlabe
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280 vagal=sum(TFDs(HFC,1:k)); symto
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282 plot(J,symtopar); %plot(A,symto
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284 4. Remove the constant levels a
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286 Make sure the agreement is quit
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288 B.2.6 Principal Components Anal
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290 Columns 12 through 15 'LF_pcoh_
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292 I= 1.0000 -0.0000 -0.0000 -0.00
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294 variances = 3.4083 1.2140 1.141
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296 B.2.7 Cluster Analysis Program
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298 end [R,C]=size(Data); if length
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300 B.2.8 Cross-correlation Program
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302 C.3 Partial coherence of HR and
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304 [13] Madwed, J., and R. Cohen.
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306 [41] Mallat, S. G., "A Theory f
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[70] Tazebay, M.V., R.T. Saliba and
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